Keywords: Wet hydrogen peroxide oxidation; Synthetic pharmaceutical wastewater; Pretreatment method. Abstract. Wet hydrogen peroxide oxidation of synthetic pharmaceutical wastewater as a pretreatment method was investigated. The reaction parameters, such as reaction temperature and time, pH and the additional amount of H 2 O 2 , were examined using a batch reactor with COD removal rate as a standard for assessing. Results showed that the highest removal rate of COD was obtained at 240 ºC for 60 min with the H 2 O 2 additional amount 2 mL. HPLC analysis results showed that the pollutants in synthetic pharmaceutical wastewater were converted into small molecule carboxylic acids after the reaction, therefore the biodegradability of wastewater was enhanced. Wet hydrogen peroxide oxidation treatment displayed effectively for the pretreatment of synthetic pharmaceutical wastewater.