A literature review of experimental measurements of mass specific extinction coefficients, sigma(s), for combustion-generated particulate has been conducted to obtain an improved value of the constant in the frequently used expression for the Planck mean absorption coefficient through smoke, kappa(m)=C(0)f(v)T. This expression, which results from the product of the spectral absorption coefficient for smoke particles and the Planck spectral distribution curve integrated over all wavelengths, is used to simplify radiative transport calculations in combustion systems. It is shown that a value of C-0=2370+/-240 m(-1) K-1 is consistent with the available data and that this value is approximately two times the values commonly used. Using the available experimental values of sigma(s) to calculate C-0 eliminates the problems associated with the large uncertainties in soot refractive index encountered when Rayleigh theory is used to predict C-0 . It is also shown that a value of K-e=8.8+/-0.9 for the dimensionless extinction coefficient is consistent with the available experimental data. These values are valid for stoichiometric and overventilated combustion only.