Mono-octanoin (Mo) is the drug of choice in the topical litholytic treatment of residual gallstones following cholecystectomy. Although this drug does not produce significant side effects, it requires a lengthy period of treatment (15-20 days). The purpose of this study was to verify the in vitro efficacy of the mixture Mo + 10% H2O vs pure Mo in human cholesterol stones. The findings indicate that this mixture can reduce dissolution time by 15.8% and increase the dissolution rate by 27.9% vs pure Mo. A further significant reduction (p = 0.0001) in dissolution times can be obtained by constant exchange of the solvent at the surface of the stone (stirring).