The main purpose of this research is to evaluate the hydrochemical properties, con-trolling processes and metal concentrations in Kaka-Reza river water (Lorestan province). To this end, 15 water samples were collected and physicochemical prop-erties (pH-EC), cation-anion contents along with concentrations of some heavy metals were determined using the standard analytical methods. The results revealed that major cations and anions concentration varied as following sequences Ca > Mg > Na+K and HCO3 > Cl >SO4, respectively. According to piper diagram, the hydro-chemical type of the water samples are found as bicarbonate-calcic, due to carbonate nature of the exposed rocks in the region. Based on the results of hydrochemical analyses, it was also revealed that rock dissolution and reverse ion exchange are dominant processes which control the chemistry or river water. In terms of heavy metal concentrations, it was found that cadmium and arsenic concentration tend to increase along the river, probably due to their anthropogenic inputs (agricultural activities). By considering the variation of other metals in the river water and taking into account the results of principal component analysis (PCA), it was assumed that these metals are mostly of natural (geogenic) source. It was also found that river water quality is currently suitable for irrigation purposes.