The purpose of this article is to study the quality of liquid fuels offered in the trade network of Popovo city, Bulgaria. Тhe color of liquid fuels is inherent and characteristic, but different hues are observed in motor gasolines, probably due to the presence of artificial additives, dissolved resins or ethyl liquids. The diesel fuels sold from „B“, „C“ and „E“ are cloudy and they are found to have comparatively lower mobility than the others. The presence of opalescence or the content of mechanical impurities in gasoline and diesel fuels is not observed. Gasoline samples taken from „E“ and „D“ are substandard due to their increased density. The diesel fuels offered by „A“, „D“ and „E“ are non-standard, due to their density not being consistent with the standardized norms. The obtained flame temperature of the diesel fuels is in accordance with the regulatory requirements. Gasoline and diesel fuels do not contain water-soluble acids and bases, with the exception of „E“ brand diesel fuel.