In the United States, HCFC-141b was phased out of urethane foam applications on January 1, 2003. Zero ozone depletion potential (ODP) alternatives, such as hydrofluorocarbons (HFCs) and hydrocarbons (normal pentane, isopentane, and cyclopentane), have been introduced to replace HCFC-141b. However, none of these alternatives can match the performance of HCFC-141b in terms of handling, economics, and overall final product performance. In particular, the fire performance of hydrocarbons-based foams cannot reach the performance previously achieved with HCFC-141b. trans-1,2-Dichloroethylene is a liquid at room temperature (b.p. 48 C). It does not deplete the ozone layer1, and it has very low global warming potential (GWP) because it has very short atmospheric lifetime. We have recently reported that when trans-1,2-dichloroethylene is used in urethane foams with hydrocarbons, it could improve the fire performance of the foams, based on a small-scale fire test (Mobil 45). In this paper, we report physical properties of hydrocarbons/trans-1,2-dichloroethylene foams, such as dimensional stability and compressive strength. We have also extended our studies of the use of trans-1,2-dichloroethylene, and report on the fire performance of HFC-blown urethane foams incorporating trans-1,2-dichloroethylene2.