The paper focuses on the assessment of selected physicochemical properties of microemulsion containing 5% by mass (m/m) of surface active compounds (SAC), i.e. Span20 and Crilet4 as well as 10 % (m/m) of distilled water dispersed in diesel fuel (DF). In particular temperature dependent properties such as: flash point (FP) and cold filter plugging point (CFPP) as well as lubricity, friction coefficient, corrosiveness and kinematic viscosity of tested fuels were examined. It was found that the

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... ted surfactants and water added to DF increase microemulsion FP by 13 ºC. For this reason, it can be stated that tested microemulsion is safer than typical DF. On the other hand it was found that the CFPP of the tested microemulsion is also adequately higher. It means less usefulness of such fuel during winter periods. Based on the research results it can be stated that addition of tested surfactants slightly worsens the lubricity of DF. However, the same surfactants in the presence of dispersed water reduce the friction in the tribological node and improve the lubricity of the tested microemulsion. Research showed that tested microemulsion system is not corrosive as well as its kinematic viscosity meet requirements of EN590 standard. Based on all these findings, microemulsion is considered as safe and such fuel can be recommended for engine tests without the risk of its damage.