An organo-modified Boehmite (OMB) was used to prepare nanocomposite UV-cured coatings, based on an innovative photopolymerizable siloxane-modified acrylic formulation, for possible use as protective coatings. 3 wt.% of the nanofiller was dispersed into the mixture in the presence of a proper photoinitiator for UV curing. Different amounts of a silane coupling agent were added to the mixture in order to enhance the compatibility between the nanofiller and the siloxane-modified acrylic formulation. The kinetics of the radical photopolymerization reaction, induced by UV radiations, was studied by photo-calorimetric analysis. The rheological behaviour of the formulations produced was studied as function of the shear rate using a plate and plate rheometer. The formulations, coated on a glass substrate, were photo-cured by using a medium pressure Hg UV lamp. On the coatings photo-polymerized in air were measured: gel content, transparency, scratch and surface hardness. The water absorption effect of the coating based on the novel organic photo-curable nanocomposite on walnut wood elements was evaluated.