This experimental investigation was conducted to assess the effect of zero point of charge (ZPC) environment on fracture behavior of rocks. The material parameters selected for this purpose were fracture toughness and specific work of fracture. These properties were determined for three rock types in five environments. Semi-circular bend specimens of dolomitic limestone, Sioux quartzite and Westerly granite were tested in aqueous solutions of aluminum chloride, calcium chloride and polyethylene oxide, all at ZPC conditions. These rocks were also tested in atmospheric air and distilled deionized water. For every rock type, the results obtained for the tests done in each of the ZPC environment were statistically compared with the results in water. This comparison was also made for air and water. The average fracture toughness in each of the ZPC environments, for all three rock types, was found to be less than the corresponding average in water. The specific work of fracture results also indicated reduction in ZPC environments as compared to water. The statistical analysis of the results, however, showed that this reduction was significant in some but not all of the rock-environment combinations tested in this investigation. / Master of Science