A method is presented to perform direct photoconductivity measurements of Sr0.61Ba0.39Nb2O6:Ce crystals at high intensities: A high voltage is applied to the sample and subsequent illumination yields a photocurrent through the crystal which charges a capacitor. Finally an electrometer measures the voltage of this capacitor. From voltage, capacity and exposure time the photoconductivity is calculated. Measurements with light pulses of a Q‐switched frequency‐doubled Nd:YAG laser (pulse duration 20 ns, light wavelength 532 nm) are performed. The photoconductivity &sgr;phincreases sublinearly with light intensityIaccording to &sgr;ph∝Ixwithx<1. The experimental results point to Ce3+/4+as the dominant photo‐ refractive center in Sr0.61Ba0.39Nb2O6:Ce at high intensities. ©1996 American Institute of Physics.