The present invention relates to the production and utilization of renewable fuel for diesel engines and heating devices usually named as biodiesel, consisting of fatty acid methyl esters. The present invention is a method for conversion of vegetable oil to biodiesel in one stage process at atmospheric pressure and low temperature without synthesis of glycerol as a by-product. The objective has been achieved by the reaction of vegetable oil with methyl formate at 28-32°C, using potassium tert-butoxide solution in tert-butanol or tetrahydrofuran as catalyst during 30-45 minutes at predefined methyl formate to oil and catalyst to oil molar ratio. Biodiesel was obtained with FAME content of at least 90%, flash point, density, viscosity, carbon residue, and cold flow properties according to the standard LVS EN 14214+A1 simultaneously with by-product - mixture of glycerol monoformate, glycerol diformate and glycerol triformate, and glycerol with glycerol content less than 9%.