1,2-Dichloro-1,1,2-trifluoroethane is a volatile liquid chlorofluoroalkane composed of carbon, hydrogen, chlorine and fluorine, and with structural formula CClF2CHClF.

[1] 1,1,2-Trichloro-1,2,2-trifluoroethane can be biotransformed in sewage sludge to 1,2-dichloro-1,1,2-trifluoroethane.

[2] The critical temperature of R-123a is 461.6 K (188.5 °C; 371.2 °F).

[3] The rotation of the molecule appears to be hindered by the present of chlorine on each carbon atom, but is eased at higher temperatures.

[3] Although not deliberately used, R-123a is a significant impurity in its isomer, the widely used 2,2-dichloro-1,1,1-trifluoroethane (R-123).