Petrus Leonardus Rijke (11 July 1812 – 7 April 1899) was a Dutch physicist, and a professor in experimental physics at the University of Leiden.

From 1830 Rijke studied physics under Pieter Johannes Uijlenbroek [de] at the University of Leiden, where he obtained his Ph.D. in 1836.

There he started a physics laboratory with a large collection of scientific instruments.

He retired in 1882, and was succeeded by Heike Kamerlingh Onnes as professor of experimental physics at the University of Leiden.

Rijke became a member of the Royal Netherlands Academy of Arts and Sciences in 1863.