The vapour-phase photolysis of methyl formate has been studied in the temperature range 30–103°C. Methoxyl, methyl and formyl radicals are generated in the photolysis and their reactions have been studied. In this temperature region, radical-radical reactions have been shown to be more important than reactions involving hydrogen atom absotraction from methyl formate by the radicals, and rate constants have been measured or deduced for several such reactions.