The important feature which is considered is to improve the adsorption efficiency of hydrogen sulphide from hydrocarbon fuels such as petroleum oil by applying the zinc oxide as nano catalyst. Totally, the optimum conditions to eliminate the hydrogen sulphide from petroleum oil are evaluated in this paper, experimentally. In this paper, zinc oxide nano particles are synthesized and are contacted with flow of sour petroleum. A method of removing sulphur from sour oil by nano catalyst is a novel method. ZnO nano catalyst of 35 nm in diameter is used to treat the sour oil. The useful correlations are presented to predict the optimum conditions for sweetening of crude oil by ZnO as nano catalyst.