We have studied the electrical and optical properties along with light induced degradation of a‐Si:H, Cl films prepared by electron cyclotron resonance (ECR) plasma. We find that there is an irreversible decrease in dark conductivity of these films after vacuum anneal at 200°C. The degradation in photoconductivity of these films due to the Staebler‐Wronski effect is smaller than that observed in glow discharge prepared a‐Si:H films.