For a number of methods used in the cooling heat treatment technique, are required quenching media with cooling rate lower than that of water and larger than that of oil. This can be achieved in industrial practice by using the synthetic quenching type media like gels or emulsions. The synthetic quenching coolants offer advantages such as non-flammability, safety of use and low cost price. The cooling medium to be tested is emulsifiable oil dissolved in water at various concentrations and the testing temperature is 50°C. In the paper were measured cooling curves for specified synthetic media and calculated for the same media the cooling rate variation and heat transfer coefficient on intervals. The experimental data were compared with those obtained from traditional media: water and heat treatment oil TT 50.