ABSTRACT: Latent fingerprints are valuable pieces of evidence that are often found when a crime has been committed. This type of evidence is hardly visible so the application of techniques to make it more visible is necessary. Furthermore, latent fingerprints can be found in wet environments, and these surfaces can be wet by water from several sources that differ in their pH and particulate matter, such as rain, roadside, canal or sea water. Small Particle Reagent (SPR) is an advantageous technique for latent fingerprint detection on wet surfaces. In this study, surface samples were moistened by soaking in various solutions to represent water from different sources. Eleven formulae of SPR, three (SPR I, II, III) from the published references and eight new modified ones, were investigated to evaluate the optimal formula for latent fingerprint detection on wet non- porous surfaces. The best quality of developed latent print was obtained from the SPR containing molybdenum disulfide in tergitol NP-7 and choline chloride. However, on a dark surface, the best quality was obtained from a suspension containing zinc carbonate as small particles. The soaking solutions used in this study did not affect the effectiveness of SPR. Nevertheless, the salt solution affected the fingerprint impression.