Rate constants for the reactions of hydroxyl radicals (OH) with 1,1,1,3,3,3-hexafluoroisopropyl methyl ether (CH3-O-CH(CF3)(2)) and 4-bromo-3-chloro-3,4,4-trifluoro-1-butene (CH2=CH-CFCl-CF2Br) have been measured over the temperature range 230-370 K to give the following Arrhenius expressions: k(CH3OCH(CF3)2)(T) = 7.69 x 10(-14) x (T/298)(2.99) x exp(+342/T), cm(3) molecule(-1) s(-1), and k(CH2CHCFCICF2Br)(T) = (6.45 +/- 0.72) x 10(-13) x exp{+(424 +/- 32)/T}, cm(3) molecule(-1) s(-1). Atmospheric lifetimes of compounds were estimated to be 67 days and 4.5 days, respectively. UV absorption spectrum of CH2=CH-CFCl-CF2Br between 164 and 260 nm and IR absorption spectra of both compounds between 450 and 1600 cm(-1) were measured at room temperature.