Hydrocarbons production with carbon numbers above C2 through methane coupling has been a target of many researches in the past decades. Recently we discovered that the reaction also occurs under supercritical water conditions. In this work, effects of reaction parameters such as catalyst Mn loading, charged catalyst amount, reaction time as well as reaction pressures and temperatures on the catalytic methane coupling under sub- and supercritical water environment were explored over MnO2/ZrO2 catalyst using a batch reactor. It was found within the investigated parameters that methane coupling activity was maximum at 12�35 MPa, 365�400 °C, 10 wt Mn loading on ZrO2, reaction time 5 min and 1.0 g catalyst charging. It was conjectured from the temperature�pressure mapping of products that the reaction pathway of hydrocarbon formation over MnO2/ZrO2 is not the same with methanol formation pathway. © 2021