It is known that the quality of diesel fuel is characterized by both performance indicators and environmental properties of fuel. At the same time, the introduction of modern norms and standards that are associated with the modification of the component composition of fuel sets the task of controlling the physicochemical properties of diesel fuels. To solve the task, fuel samples, purchased from different fuel producers, and diesel fuel samples with an unknown prehistory, stored for a long time in the laboratory, were investigated. Mixtures of fuel with kerosene were also investigated. Diluted kerosene fuel, when it is used, reduces not only the power, but also the engine life. The density of the objects of the study was measured with oil meters. The viscosity and fractional composition of the fuels were determined using the VPZh-4 viscosimeter and the ARNS-1E oil distillation apparatus, respectively. Cetane numbers were measured by the OCTAN-IM indicator. As a result of the carried out researches it is established that the density, viscosity, fractional composition of diesel fuels correspond to those presented in the GOST standards. The acidity of samples with a long storage time and an unknown prehistory is greater than the GOST indicator value. The average value of the cetane number of diesel fuels measured by the OCTAN-IM indicator and different from the parameters required by the regulations is identical to the value given in the world fuel charter standard (ISO 5156). In all, without exception, fuels are present unsaturated and aromatic hydrocarbons. It is shown that in the fuel produced by different manufacturers, the ratio of unsaturated and aromatic hydrocarbons can be different. The density, viscosity and other characteristics of the mixture containing 10% kerosene are identical to the normalized values for diesel fuel. The density of the mixture containing 30% kerosene is not only below the norm, but also below the measured values of the density of diesel fuels.