Abstarct: Ka-Ka Reza river is one of the major rivers flowing in the Chaghlvandi catchment Lorestan province. The purpose of this study is to assess water quality and geochemistry of river sediments and their possible pollution. For this purpose, 15 water samples and bed sediment samples were collected along the river .In order to evaluate the hydrochemical quality of water samples concentration of main anions and cations, also nitrates and heavy mextals were measured. The concentrations of heavy mextals and some physicochemical parameters (organic matter content, texture and pH) of sediment samples were also determined using standard methods. The results of hydrochemical analyses showed that the quality of Ka-Ka Reza river is mainly influenced by lithological units out cropped around the river. Concentration of major ions in the river water exhibited a decreasing trend, which is due to increased discharge of water along the river. Interpretation of water quality data reveals that main hydrochemical type of water samples is calcic bicarbonate, hard and alkaline in nature. Processes such as dissolution, ion exchange, and human inputs lead to changes in concentrations of anions, cations and water quality. baxsed on calculation of saturation Indexes, the water samples are under-saturated with regard to halite, anhydrite and gypsum while are saturated relative to calcite and dolomite. it was also found that the river water is generally suitable for drinking purposes and slightly saline for irrigation purposes. In terms of heavy mextals concentration, the river water is not yet contaminated, concentration of all mextals are lower the permissible limits recommended by WHO. Granulometric analysis revealed that the sediment samples are texturally sandy gravel, gravel sandy, sandy gravel mud and gravel. Results of geochemical analyses also showed that sediment samples have low content of As, Cr, Zn, Cu and Ni compared to their corresponding concentrations in world mean sediments whereas Cd concentration in all sediment samples is higher than it,s limit. Calculation of geoaccumulation indexes for mextals revealed that the sediment samples are not contaminated by heavy mextals such as Cr, Fe, Ni, Cu and Pb and Cd concentration in same sampling points leads to low contamination. baxsed on the results of the multivariate statistical analyses it was found that Fe, Ni, Zn and Cr are mainly from natural origin whereas Pb, Cd and As in sediments are likely to be from anthropogenic source (Agricultural and urban runoff).