A technique of contact angle measurement was applied to the nano-scale oxide-supported metal particles. For Cu supported on ZnO and ZrO₂ the angles were found to increase and the work of adhesion to decrease with increasing particle size. Such a trend is interpreted as an effect of negative contact line tension of 2.1 × 10^-9 J m^-1 and 1.0 × 10^-9 J m^-1 in the Cu/ZnO and Cu/ZrO₂ system, correspondingly. For the small-sized Cu particles the apparent work of adhesion on ZnO support is higher than that on ZrO₂.