The invention relates to the realization of synthesis of organic com¬ pounds or abatement of volatile organic compounds (VOCs) in gas-solid fluid- ised bed photocatalytic reactor with improved illumination efficiency. The photoreactor consists of a two-dimensional fluidized bed catalytic reactor with two walls transparent to ultraviolet radiation, by an illumination system based on an array of LEDs positioned near its external walls, and heated by Joule effect inside the catalytic bed to control the reaction temperature. Through the use of the reactor it is possible to carry out both partial and total oxidation re¬ actions with high activity and selectivity and, in addition, the illuminated cata¬ lyst surface area per unit of irradiated volume reaches values in the order of 106 m"1, significantly higher than the values typical of microreactors and slurry reactors. The photocatalytic system reported in the present invention is shown to have high illumination efficiency due to the use of UV-LEDs, which, ensur¬ ing a direction of light irradiation orthogonal to the emission point, minimize the dispersion of photons.