From a review of existing correlations for K P the partition coefficient of semi-volatile organic chemicals (SOCs) between aerosol and gaseous phases, it is suggested that the octanol-air partition coefficient (K O A ) may be a valuable direct descriptor of SOCs volatility and may be preferable to the use of the experimentally inaccessible subcooled liquid-vapor pressure. Successful two parameter correlations are developed between log K P and log K O A , and an even simpler one parameter correlation is suggested that the ratio K P K O A is approximately constant for a class of SOCs.