Pentaerythritol partial-esters were synthesized and their physical properties, thermal stabilities, heat of adsorption, and lubricity were investigated. It was found that the hydroxyl groups involved in the partial-esters exerted some important effects on their properties. The partial-esters showed higher viscosities than their respective full-esters due to the association of their molecules. They adsorbed strongly onto metal surfaces to control corrosion of the metals, and to give better boundary lubricity.