The optical absorption coefficient &agr; of doped and undoped hydrogenated amorphous silicon (a‐Si:H) has been measured for photon energies from 2.2 to 1.0 eV using photo‐pyroelectric spectroscopy (PPES). A simplified experimental setup and analysis for extracting &agr; from the PPES data are described. In PPES the temperature rise induced in thea‐Si:H thin film due to weakly absorbed light is detected via a pyroelectric polymer in thermal contact with the sample. This technique presently has a sensitivity of &agr;d≳10−3, wheredis the sample thickness.