In this paper, the results of a study about using Nickel and Copper nanoparticles in a base oil, which is used for engine oil production, are presented. The size characterization and morphology of nano- particles were determined byAtomic Force Microscopy, Electron scanning microscopy and X- ray diffractometry. Dispersion of nano- particles in base oil was achieved by ultrasonic homogenizer and the antiwear abilitywas evaluated by four ball test. The size determination results of threemethods conformed to each other and also with nominal sizes claimed by supplier. The morphologies determined for both nano- particles vouched supplierÂs claims, too. Coppernano- particles improved antiwear property of base oil but nickel nano- particles did not affect this property.