Magnesite and dolomite are salt-type minerals that show similar chemical composition and flotation behavior due to same crystal structure, and sparingly soluble nature. The surface properties of minerals play a major role in determining their separation from each other in processes such as flotation. During flotation process, selectivity problem arises between magnesite and associated gangue minerals such as dolomite. There is a close relationship between floatability of minerals and their contact angles. Therefore, surface hydrophobicity of magnesite and dolomite minerals was investigated by contact angle measurements in the absence and presence of flotation reagents. Magnesite and dolomite show hydrophilic properties and they have got a small contact angle (magnesite similar to 10.4 degrees and dolomite similar to 6.6 degrees) in distilled water in the absence of any surfactant. The contact angle values at the magnesite and dolomite surfaces remained at 9.7 degrees-10.9 degrees in the presence of petroleum sulphonates (R825 and R840) while sodium oleate affected hydrophobicity of magnesite, and the contact angle value increased up to 79 degrees. The contact angle value of 39 degrees at dolomite surface was obtained in the Solution of sodium oleate, respectively. (c) 2005 Elsevier B.V. All rights reserved.