In the present work, we have investigated photoconductivity properties in Pr-doped ZnS powders. ZnS: Pr powder has been prepared by simple heat treatment technique at temperature of 800 0 C. I-V characteristics i.e. voltage dependence of photocurrent under UV illumination (λ=365 nm) exhibits non-Ohmic (r < 1) behavior at low as well as high voltage regimes. The crystallite size of ZnS:Pr corresponding to main XRD peak is estimated as 37.25 µm. The micro strain is calculated as 0.46.