Are there any chances to increase oxygenates yield in partial oxidation of methane (MPO) to economically efficient level? The effect of various homogenous promoters of MPO was studied in terms of their role in the MPO mechanism on vanadia silica supported catalyst. Accordingly they were classified into three groups: equilibrium shifting (H2O), reducing (H-2) and intermediate supplying (MeOH, EtOH, CH2Cl2). The most profound promoting effect was exhibited by H-2, which decreased MPO temperature by 50-520 degrees C, at which unpromoted MPO gave no products. Among organic promoters the most efficient with respect to the added amount appeared ethylene, which enhanced both formaldehyde yield and methane conversion and also methanol. In the presence of these promoters the achieved HCHO yield was comparable to the highest values reported in the literature (1200 g HCHO per kg catalyst per h). The contribution of organic additives to the formaldehyde yield was experimentally excluded. (c) 2005 Elsevier B.V. All rights reserved.