An improved model for the calculation of radiative transfer in enclosures filled with an absorbing, emitting and scattering medium is presented. The model is denoted by a hybrid six-flux/zone model since it combines features of both the zone method and (three-dimensional) six-flux models. Compared to the zone method, computation time is considerably reduced and reaches approximately the same order as the faster flux-type models. The accuracy of the hybrid six-flux/zone model presented here is drastically improved without increasing computation time. This is achieved by introducing a correction for the directional characteristics of the propagation of radiation through adjacent zones. The thus improved hybrid model is evaluated for a realistic recognized test problem and found to be an efficient and accurate tool for calculating radiative transfer in enclosures filled with a participating medium.