Abstract: An inverse analysis for simultaneous estimation of the radiation phase function and the single scattering albedo in natural waters, from the knowledge of radiation, is presented. The analysis involves a forward model that utilizes an analytical discrete-ordinates method for solving the radiative transfer equation \cite{Chalhoub1997,ChalhoubandGarcia1998}, and an inverse model which contains an algorithm for least-squares estimation that is iteratively solved for retrieving the desired optical properties by using the Levenberg-Marquardt optimizer \cite{Levenberg1944,Marquardt1963,IMSLM1991}. The experimental data are simulated with synthetic data corrupted with noise. The results show that the optical properties can be recovered with high accuracy, even for very noisy data.