Abstract This study of the radiation field generated in a cylindrical photoreactor irradiated from the bottom presents the theoretical foundations of a method for the experimental verification of three different radiation models. The expressions representing the local volumetric rate of energy absorption (LVREA) were formulated and applied to the prediction of the rate of an actinometric reaction. This reaction takes place inside a microreactor operated in a batch recycling system with polychromatic radiation. The values obtained portray the same behaviour as that of the energy densities calculated previously (Part I), thus becoming a valid, accurate method for the experimental measurement of the absolute values of the radiation field that are sought after (volumetric rate of energy absorption). The proposed approach is able to produce quasi-point values of the absolute values of the VREA at the microreactor as an excellent approximation to the absolute values of the LVREA (local measurements). The present work also points out the qualitative and quantitative discrepancies of the results predicted by the line models when compared with those of the extense source model with volumetric emission.