Herman Ambrosius Jan Baanders (Amsterdam, 13 February 1876 – Amsterdam, 27 May 1953), also known by his initials as H.A.J. Baanders, was a Dutch architect, designer and entrepreneur who was active in the Amsterdamse School style of architecture. He designed the Amsterdams Lyceum, among others.
Baanders' most significant contribution to the development of the Amsterdamse School style was a number of buildings outside Amsterdam during the early phase of the movement. His firm was also the starting point for the careers of a number of prominent Amsterdamse School architects, such as Michel de Klerk, Cornelis Blaauw, J. Zietsma, and Willem Maas.
In Amsterdam a street has been named for him, the H.A.J. Baanderskade in Zeeburg.
H.A.J. Baanders followed in the footsteps of his father, the architect Herman Hendrik Baanders (1849–1905). Like his father, he studied architecture (bouwkunde) at the Industrieschool van de Maatschappij voor den Werkenden Stand in Amsterdam. After completing his studies, he worked for his father as well as for the architect Pierre Cuypers. In 1899 he settled in The Hague, where he was employed by the government agency in charge of schools and other educational buildings. In 1903 Baanders returned to Amsterdam to assist his father.
In addition to architecture, he was also active in furniture and interior design. He was instructed in batik design by Maurits Greshoff and showed his batik work at an exhibition of Dutch decorative arts held in 1904 at the Museum of Decorative Arts in Copenhagen. He also wrote an article on batik, "Over de toepassing der batik-kunst in Nederland" ("On the Application of Batik Art in the Netherlands"), published in the volume De batik-techniek (1900).
After the death of his father in 1905, Baanders took over his father's architectural firm and carpentry workshop. The first mention of Baanders as an independent architect was in 1906, when he moved his offices from Ruysdaelkade 27 to Prinsengracht 955, in a building designed by Baanders himself. From 1909, his offices were at Herengracht 495. The company moved next-door, to Herengracht 493, in 1924. After World War II, the company returned to Herengracht 425.