Photoluminescence in hydrogenated amorphous carbon thin films deposited using the dc saddle‐field glow‐discharge technique onto glass and single‐crystal silicon substrates was studied. Samples prepared using positive substrate bias exhibited strong broad‐band photoluminescence at room temperature. The luminescence spectrum had a major peak at 1.9 eV and two smaller peaks at 2.3 and 2.6 eV. Samples prepared using grounded or negatively biased substrates exhibited only weak photoluminescence near 2.6 eV. Infrared spectroscopy indicates that the luminescence at 1.9 and 2.3 eV is related to the presence of C–OH bonds, whereas the photoluminescence at 2.6 eV appears to be an intrinsic property of thea‐C:H films. ©1996 American Institute of Physics.