The present paper reports the effect of replacement of selenium by antimony on the steady state and the transient photoconductivity in vacuum evaporated amorphous thin Mills of As30Se70-xSbx (x=2.5, 5, 7.5, 10, 12.5, 15 and 17.5 at.%). The composition dependence of the steady state photoconductivity at room temperature shows that the photoconductivity increases while the photosensitivity decreases with the increase in antimony content. The transient photoconductivity shows that the lifetime of the carrier decreases with increasing, the limit intensity. This decrease suggests that the photoconductivity mechanism in our samples was controlled by the transition trapping processes. Replacement of selenium by antimony results in a monotonic decrease in the band gap of As30Se70-xSbx thin films. This behavior was interpreted on the basis of the chemical bond approach. (c) 2006 Elsevier B.V. All rights reserved.