Originally a carpenter, Alexander Jacobus Kropholler as an architect was an autodidact. Early in his career he formed a partnership with J.F. Staal which lasted from 1902 until 1910. During this period the two architects designed several buildings in styles that are closely related to Jugendstil, although Berlagian influences are often present as well. The insurance company De Utrecht was an important commissioner for the duo. In 1910 a conflict between the two resulted in a split. Despite Staal's marriage to Kropholler's sister Margaret (who was quite a talented architect herself), the two did not speak to each other since.
In 1908 Kropholler became a catholic. He designed many churches in the following decades, often as part of a complex with houses or other buildings. As a conservative catholic and a nationalist Kropholler developed a strong interest in traditional architecture, both of his own country but of Scandinavia as well. The work Kropholler designed in this part of his career is remarkably consistent, with little or no evolution in style. Influenced by H.P. Berlage Kropholler used traditional materials, mainly brick with natural stone at places that need emphasizing only. The churches lack vaults, and the wooden roofs are left visible. Unlike Berlage, Kropholler took much of his inspiration from architecture of the past, but exaggerating traditional elements; huge stepped gables and enormous buttresses are more of a rule than an exception.
Kropholler was one of the leading architects of Traditionalism. His almost fanatical dedication to traditional style and indigenous building materials and his never ceasing criticism of architects with views other than his own did his popularity among his colleagues little good. Despite this fanatism he was not always true to his own principles. While he could rant against fake decorations and use of 'dishonest' materials, in his churches he often used hollow buttresses, and a supposedly solid oak wood beam could be made up using plywood disguising a steel H-profile beam. During World War Two Kropholler continued to work and published several articles in architectural magazines controled by the nazis, who shared his preference for traditional architecture. After the war he was sentenced for collaboration by a tribunal of vindictive colleagues. Although he soon continued his career, his golden years were over.

The following is a still incomplete list of Kropholler's work.

1903-1904 Leeuwarden (Fr): branch office De Utrecht

Building of yellow brick, with Jugendstil details.

1904-1906 Amsterdam (NH): office-building De Utrecht

Building inspired by the American skyscrapers of that time. Facade in several types of natural stone.

1905-1906 Amsterdam (NH): shop-building De Utrecht

Building with a very open facade of granite.

1905 Esbeek (NB): forester's house

Brick building with Rationalistic and Jugendstil elements, with a wooden,zinc-clad tower on top. Built on the 'De Utrecht' estate.

1906 Utrecht (U): branch office De Utrecht

Facade of polished red granite, inspired by Moorish architecture. Now a shop.

1908-1910 Velp (NB): extension convent St. Alfonsis

Entrance with tower. By Kropholler alone.

1913 Scheveningen (ZH): church O.L. Vrouwe van Lourdes

Kropholler designed a complex comprising of a church, a chapel and various houses. Apart from the houses Kropholler only completed the chapel and the lower part of the tower, due to some disagreement. C.M. van Moorsel designed a new church which was built in 1924-1925. Kropholler completed the tower in 1965.

1914-1915 Beverwijk (NH): church O.L. Vrouw van Goede Raad

Kropholler's first church already shows many elements he would continue to use; heavy buttresses, the accentuated chimney, small windows and a minimal use of natural stone and ornaments. Also a tower with saddle-roof and a rectangular choir.

1916 Tilligte (OV): church S.S. Simon en Judas

Church in Traditionalistic style. Tower with portal at the side of the front. Choir lower than the nave.

1919-1921 Den Haag (ZH): church St. Paschalis Baylonkerk

A church with an intentional 'village church look'. Square tower with spire. Polygonal choir. The church was built diagonally on the terrain in order to get the choir at the east-side.

1919-1920 Bornerbroek (Ov): church St. Stephanus

Kropholler rebuilt a neo-Gothic church. Added tower, choir and tower.

1919-1920 Brunssum-Treebeek (L): church St. Barbara

Simple church in Traditionalistic style. A tower was planned but not built. In 1951 the church was extended and given a new front, also by Kropholler.

1920 Apeldoorn (G): servants houses

Five houses on the estate of the Kröller-Müller family, in traditional style. Walls of brick, the upper part of the gable with wooden planks. Shagged roofs.

1920 Den Haag (ZH): shop

No further details.

1921 Ursem (NH): church St. Bavo

Church in Traditionalistic style.

1921 Amsterdam (NH): church St. Rita

Church in Traditionalistic style. Kropholler also designed two schools that formed a complex together with the church, and to which in 1926 the St. Rosa convent was added.

1924-1928 Amsterdam (NH): Linnaeushof and church H.H. Martelaren van Gorcum

Complex with a church, a monastery, a school and houses. The church has a large, closed facade and a big square crossing-tower.

1926 Amsterdam (NH): St. Rosa convent

No further details.

1927 Den Haag (ZH): houses Kwartellaan

86 houses in Traditionalistic style.

1928-1930 Rotterdam (ZH): church St. Antonius

Church with a T-shaped floorplan, with the altar in the center. Demolished 1973.

1929-1931 Alkmaar (NH): Hooge Huys

Office-building for insurance company Noord-Hollandsche Levensverzekering-Maatschappij. Tall roof with stepped gables, entrance at the corner.

1930-1934 Rotterdam (ZH): Bank Mees & Zoonen

Two older buildings rebuilt into a single building.

1930 Noordwijkerhout (ZH): town hall

Town hall in Tradionalistic style, with tall stepped gable.

1931-1932 Waalwijk (NB): town hall

The first of a number of buildings around Waalwijk's town hall square Kropholler would design until 1962. The bricks used are of a special type, larger than usual. The stepped gable gives the building an instantly monumental appearance and is representative for much of Kropholler's work. An earlier design for the town hall shows a symmetrical building with a tower flush with the facade.

1932-1934 Affligem, Belgium: enlargement monastery

New wing and chapel. Design includes a church with two towers at the front, with another two towers at the back, which is not built.

1932-1933 Neerbeek (L): church St. Callistus

One-aisled church in Traditionalistic style. Transept-arm on the southern side only, another arm was planned on the north side but not built.

ca. 1933 Tancremont, Belgium: Benedictine monastery

No further details.

1933 Soesterberg (U): chapel Missiehuis St. Jan

No further details.

1933-1934 Vught (NB): church Maria Middelares Aller Genade

Instead of a conventional tower this church has a square tower-like heightened choir.

Convent with chapel and school.

1933-1936 Eindhoven (NB): Van Abbemuseum

The building for this arts museum was commisioned by sigarfactory-owner H.J. van Abbe, hence the name. It makes a very closed appearance from the outside. A plan by A. Cahen in the 1990's to enlarge the museum by mutilating it was not executed.

1934- Egmond-Binnen (NH): Benedictine monastery St. Adelbert

Design for a big complex on the site of a vanished medieval monastery. Only partly executed, and after World War Two completed by Koldewey.

1935 Tilburg (NB): Pension Mariëngaarde

L-shaped complex in Traditionalistic style, with chapel.

1936 Leiden (ZH): church St. Petrus

Church with a tall tower in plain traditional style, enormous buttresses, clean brickwork and only a few pieces of natural stone. Three-aisled church, with a wide central aisle. Kropholler's ideal that a church should be at the centre of a neighbourhood came true here, as he also designed the adjacent houses.

1936-1937 Nijmegen (G): chapel St. Canisiuscollege

Three-aisled, towerless chapel with big buttresses. Demolished in 1986.

1938 Wateringen (ZH): town hall

Similar in style to the town hall in Waalwijk.

1938-1939 Venlo (L): church H. Familie

Three-aisled church in Traditionalistic style, with square tower and rectangular choir.

1939-1940 Oosterbeek (G): chapel Mariëndaal estate

Octagonal chapel in Traditionalistic style, built by commission of the Oxford Movement.

1939-1941 Heesch (NB): rebuilding town hall

Alterations to the exterior of a town hall dating from 1839. In conjunction with P.G. Elemens.

1940 Leidschendam (ZH): town hall

Townhall in imitated 17th-century style.

1940 Wanssum (L): town hall

Building in Traditionalistic style. Destroyed in 1944 and rebuilt in 1954.

1940-1942 Medemblik (NH): town hall

Building very similar to the town hall in Waalwijk.

1941-1942 Grou (Fr): town hall

Town hall in Traditionalistic style, with a bent saddle-roof.

1947 Nijmegen (G): church St. Franciscus van Assisië

Three-aisled basilica. Side-aisles with gables at the front. Officially designed by architecture office Van Oerle en Schrama, in conjunction with Kropholler. It's possible that, considering his controversial role during the war, like many other artists Kropholler had difficulties continuing his career under his own name after the war.

1949-1951 Arcen (L): town hall

Designed in conjunction with R.J. Veendorp. Tall roof with small tower on top.

1952 's-Hertogenbosch (NB): church H.H. Harten

Three-aisled basilica, largely similar to the St. Franciscus in Nijmegen (1947). Side-aisles with gables at the front. Part of the original design was a tower, which was planned next to the front of the church but was not built.

1953 Soesterberg (U): chapel Contact der Continenten

Chapel for an older complex. No further details.