The values of absorption coefficients of gasoline fuel (BP Pump Grade 95 RON ULG (research octane number unleaded gasoline)), 2,2,4-trimethylpentane (iso-octane) and 3-pentanone have been measured experimentally in the range of wavelengths between and . The values of the indices of absorption, calculated based on these coefficients, have been compared with those previously obtained for low sulphur ESSO AF1313 diesel fuel. These values are generally lower for pure substances (e.g., iso-octane and 3-pentanone) than for diesel and gasoline fuels. The values of the average absorption efficiency factor for all fuels are approximated by a power function , where is the droplet radius. and in turn are approximated by piecewise quadratic functions of the radiation temperature, with the coefficients calculated separately in the ranges of droplet radii , , , and for all fuels. This new approximation is shown to be more accurate compared with the case when and are approximated by quadratic functions or fourth power polynomials of the radiation temperature, with the coefficients calculated in the whole range . This difference in the approximations of and , however, is shown to have little effect on modeling of fuel droplet heating and evaporation in conditions typical for internal combustion engines, especially in the case of diesel fuel and 3-pentanone.