In 1920, Siddiqui proceeded to University College London to study medicine. However, after one year of pre-medical studies, he moved to Frankfurt University in 1921 to study chemistry. In 1924, he married his German classmate, Ethel Wilhelmina Schneeman.
In 1920, Siddiqui began studying medicine at University College London but switched to chemistry at Frankfurt University in 1921. He married his German classmate, Ethel Wilhelmina Schneeman, in 1924.