The photochemical ozone creation potentials (POCPs) for CF3CF=CH2 and other commercially significant hydrofluoroolefins have been estimated for the first time. CF3CF=CH2 (HFO-1234yf) has a POCP of 7.0 which is less than that for ethane (12.3) and greater than for methane (0.6). Methane and ethane have sufficiently low POCPs that they are usually considered unreactive with respect to ozone formation in urban areas and accordingly are exempt from volatile organic compound (VOC) emission regulations. Estimated POCPs for other hydrofluoroolefins are: CH2=CF2, 18.0; CF2=CF2, 12.5; CH2=CHCF3, 10.7; CF2=CFCF3, 5.4; Z-CHF=CFCF3, 5.6; E-CHF=CFCF3, 7.3; CH2=CHCF2CF3, 6.6; and t-CHF=CHCF3, 6.4. (C) 2010 Elsevier Ltd. All rights reserved.