The rates of the atmospherically important reactions of the CF3O radical with methane (k(6)), ethane (k(7)), and isobutane (k(8)) have been measured at low pressure (approximate to 1 Torr) with the fast flow tube technique associated with a monitoring of the CF3O radical by laser-induced fluorescence; over the following temperature ranges, the respective Arrhenius expressions are as follows : methane (296-573 K), k(6) (4.49 +/- 1.39) x 10(-12) exp(1606 +/- 84)/T cm(3) s(-1); ethane (295-573 K), k(7) = (1.13 +/- 0.34) x 10(-11) exp-(642 +/- 113)/T cm(3) s(-1) : isobutane (298-523 K), k(8) = (1.04 +/- 0.2) x 10(-11) exp-(102 +/- 67)/T. A comparison with measurements with other techniques shows that, though our room temperature values of k(6), k(7), and k(8) are in very good agreement with most literature values, our temperature coefficients for k(7) and k(8) are significantly different from the very few other measurements available in the literature. These discrepancies are tentatively ascribed to undetected wall reactions in the highest range of temperatures.