The solvent effect of 4 concentrations of sodium hypochlorite (0.5, 1.0, 2.5, and 5.0%) on bovine pulp tissue and the level of residual chlorine, pH and surface tension before and after dissolution were studied in vitro. A fragment of bovine pulp was submersed in sodium hypochlorite that circulated in an apparatus with a peristaltic pump and Luer Lok syringe. The higher the concentration of sodium hypochlorite the faster the dissolution of the pulp tissue. All concentrations of sodium hypochlorite reduced the pH and the surface tension and the higher concentrations of the solution had the least consumption of chlorine during tissue dissolution. Thus this study indicated that residual chlorine was directly proportional to concentration in the process of pulp tissue dissolution and that there was residual chlorine at all concentrations used.