The efficiency and validity of different chemical substrates for trapping bis(methoxycarbonyl)carbene is dependent on the conditions of carbene generation. On conventional photolysis of diazomalonic ester by long-wave UV light (through pyrex filter, λ>290 nm) the most powerful trap for carbene in the series of substrates Me2S, CH3OH, C6H12 and C5H5N is dimethyl sulfide (with the efficiency ratio of ~ 6:4:2:1 correspondingly). When short-wave decomposition of diazomalonate is employed (through quartz filter, λ>210 nm) more reliable and useful chemical traps for bis(methoxycarbonyl)carbene are pyridine and cyclohexane, which adducts with carbene are rather stable at short-wave irradiation conditions. Application of alcohols for the trapping of (МеО2С)2С: proves to be preferential, when simultaneous monitoring carbene and oxoketene formation during photolysis is necessary.