The article presents results of development of a new method for temperature calculation of the multi-fuel nozzle inner wall based on data on heat flux. A patent search and an analysis of scientific and technical information on the multi-fuel nozzles were carried out. It was established that one of the most effective ways to prevent appearance and rapid formation of carbonaceous deposits in liquid hydrocarbon fuels was to reduce temperature of the metal wall. New formulae were obtained to calculate the inner surface temperature depending on the amount of heat-transfer agents and their thermophysical properties, geometric characteristics of the supply channels and the injector “dry” mass. A comparative theoretical calculation of the temperature decrease inside a single-fuel and a dual-fuel nozzles was carried out at different mass flow rates of kerosene. The results obtained indicate higher cooling efficiency of multi-fuel nozzles compared to the single-fuel ones.