The catalytic behaviour and steady-state redox properties of the precipitated silica catalyst in methane to formaldehdye partial oxidation (MPO) are addressed and basic relationships between the activity-selectivity pattern and operating conditions of the MPO process are outlined. A set of model equations, accounting for the influence of any experimental parameter (Le., T, P, P-CH4/P-O2 ratio, tau) on the steady-state conditions of the catalyst surface and activity-selectivity pattern, constitutes a theoretical background for catalyst optimization and engineering of the MPO reaction.