Transient photocurrent experiments in amorphous selenium and nematic liquid crystal double layers have been carried out to investigate the transient ion transport process in 4-cyano-4’-alkyl-biphenyl. It is found that the mobile charge carriers in the liquid crystal are positive ions with the drift mobility of 3.5 x 10(-6) cm(2)/Vs at 303 K and have the ionic radius of 0.32 nm. The numerical analysis is also carried out to gain insight into the injection process of photogenerated charge carriers from the amorphous selenium layer into the nematic liquid crystal layer.