In order to provide information about photolysis frequencies in the aqueous phase for chemical transport models including wet chemistry aparameterization which can be added to gaseous-phase photolysis models was developed. The actinic fluxes inside cloud droplet's arecalculated on the basis of rigorous Mie theory taking into account the effect of dissolved particulate aerosol material and 10 representativecloud droplet size distributions. The results show that the actinic flux inside cloud droplets are on the average more than twice as large ascompared to the interstitial air. The newly developed parameterization has been applied together with the model STAR (System forTransfer of Atmospheric Radiation). Apart from the parameters influencing gas-phase photolysis frequencies the radiation quantities insidethe cloud droplets and therefore the photolysis frequencies in the aqueous phase depend on the droplet size distribution, the mixing ratio ofdry aerosol particulate material to cloud droplet water, and the amount of light absorbing material in the droplets. In-droplet radical sourcestrengths have been calculated for the most important photolytic sources of OH and SO4-.