The purpose of the research is the theoretical justification for the use of diesel fuel mixture based on castor oil. The preferred type of biofuel used in agriculture and forestry is multi-component diesel fuel produced by mixing petrole-um diesel fuel (DF) and fuel oil. As raw materials to produce diesel fuel blends-entertainment oil crops that are not used in the food industry, such as safflower, camelina, canola, rape, crambe Abyssinian and castor. As diesel fuel blends investigated mixture ricinic oil (RicM) and summer diesel fuel (GOST 305-2013) three compositions. On the basis of the thermal calculation, the parameters of the engine operating cycle are determined and the dependences of the engine operating cycle indicators on the composition of the mixture are presented. The comparison of the ob-tained parameters with the indicators of traditional diesel fuel was made. Calorific value of mixing substance de-creases with increase in the proportion of the biological component (RicM), thermal characteristics of the gas mix-ture is practically unchanged, due to gain-eat proportion of oxygen in the elemental composition ricinic oil. With an increase in the concentration of ricinic oil in the mixed fuel, a decrease in the power of the D-240 engine by 1.8-1.9% compared to diesel fuel was noted, the consumption of the mixture increased by 6-8 % or by 2.3 g/kWh on average for every 5 % increase in the concentration of ricinic mass in the mixture. According to the calculations and comparisons with studies on other crops, DMF produced from ricinic oil has similar characteristics with mixtures based on rapeseed, mustard, soybean oils. These studies are aimed at diversifying fuel resources and increasing the energy independence of agricultural enterprises.