 He is a professor of mathematics at the Leiden University since 1975, and was chairman of the department of mathematics and computer science at Leiden from 1991 to 1993.He was also president of the Dutch Mathematical Society from 1984 to 1986.Tijdeman received his Ph.D. in 1969 from the University of Amsterdam, and received an honorary doctorate from Kossuth Lajos University in 1999.