Laboratory wastewater was derived from analytical activities in the laboratory and grouped to hazardous waste. It was different from hazardous industrial wastewater because of many different pollutants. The composition of its dangerous substances was not easy to be processed by biological process. Therefore, chemical method was tried, namely Advanced Oxidation Processes (AOPs). The optimum dose of Fenton (H2O2 and FeSO4) reagent was the purpose to reduce the concentration of Chemical Oxygen Demand (COD). Variations applied were COD concentrations, which were 10,090,09 mg / L, 5.009,01 mg / L and 511,71 mg / L with varied reagen. The optimum dose of Fenton reagent was obtained 1: 300 with COD reduction efficiency as follows: COD concentration 10,090,09 mg / L = 21,43%, COD concentration 5.009,01 mg / L = 46,76% and concentration of COD 511,71 mg / L = 83,10%. The results suggested that Fenton could to reduce COD concentration up to 80% in relatively low concentrations. Keywords: laboratory wastewater, Fenton, COD, batch