Thermal decomposition and heat treatment method is used for the preparation of ZnO and the precursor are used for this is zinc oxalate, zinc nitrate and zinc sulfate after preparation of ZnO study on its optical and electrical properties has also been performed then its photoconductivity in air and two minutes rise and fall curve also measured. Which is very useful in study of switching characteristic of materials. XRD clearly shows that prepared material has good quality of ZnO, SEM indicates that synthesized materials of wurzite structure. Two minutes rise and fall curve shows that zinc oxalate has the best switching time among all three materials