Photocatalytic oxidation of 4-methoxybenzyl alcohol to p-anisaldehyde was performed in water organic-free solutions by using a fixed bed continuous photoreactor containing Pyrex beads on which TiO₂ home prepared photocatalyst (ex TiCl₄) was supported. The influence of liquid flow rate, inlet alcohol concentration, catalyst amount and incident photonic flow on the photoprocess was studied. The highest selectivity to p-anisaldehyde was about 47% being CO₂ the other main oxidation product; traces of 4-methoxybenzoic acid were also detected. The radiation field inside the photoreactor has been modelled by applying the Monte Carlo method thus allowing the determination of the local volumetric rate of photon absorption (LVRPA). It was found the optimum amount of TiO₂ supported on the beads. The radiation modelling allowed the determination of the dependence of reaction kinetics on light intensity. The Langmuir-Hinshelwood approach has been satisfactorily applied for modelling the photoreactivity results and the values of all the model parameters have been determined.