The application of hydrophobic polymers to stone materials is an effective way to preserve stone artifacts and protect Cultural Heritage from decay. To improve the characteristics and performance of water-repellent treatments, and to avoid the use of harmful solvents, new solutions have been recently explored. The authors have recently proposed experimental photopolymerizable hybrid organic-inorganic (O-I) protective coatings, mainly intended for the surface protection of porous stones. In this paper, different analytical techniques (contact angle, colorimetric measurements, water absorption measurements, ESEM-EDS analyses) were employed to fully characterize the innovative water-repellent coatings applied on a calcareous stone substrate, typical of Apulia Region (Pietra Leccese, PL). The research work consists of two parts: the first one concerns the evaluation of the appropriate amount of the novel photopolymerizable O-I hybrid coating applied on Lecesse Stone in order to achieve better protective properties; the second one refers to the comparison of the properties of this latter coating with two commercial water-repellent products. The final performances of the innovative free-solvent photopolymerizable coating, in terms of hydrophobicity and color change, are found to be comparable to those of the commercial products.