Formaldehyde is made from methane and a molecular oxygen containing gas by using a silica supported catalyst having less than 350 parts per million by weight of sodium and having a catalytically effective amount of V.sub.2 O.sub.5. The low sodium form of the silica support can be made by washing silica gel or precipitated silica or by using a fumed silica. In general, the lower the sodium level, the better is the catalyst.