A preparation method of highly effective methane to formaldehyde partial oxidation (MPO) FeOx/SiO2 catalysts (Fe 0.09-0.43 wt%) is reported, based on "adsorption-precipitation" (ADS/PRC) of Fe-II ions under controlled conditions. The performance of ADS/PRC catalysts in the MPO reaction at 650degreesC has been compared with that of conventional systems prepared by "incipient wetness" (INC/ WET) of silica carriers with aqueous solutions of Fe-III. The ADS/PRC method, likely enabling a higher dispersion of the active phase, provides very effective MPO catalysts featuring CH4 turnover frequency (TOF) and HCHO productivity (STYHCHO) values larger than those of the counterpart INC/WET systems.