Low-temperature rate coefficients for the reactions of C2H + RH --> products (RH = C3H8, i-C4H10, n-C4H10, and neo-C5H12) have been measured over the temperature range 154-361. K. Measurements were made using laser photolysis of C2H2 to produce C2H. Transient infrared laser absorption decays of C2H are used to monitor the subsequent reaction in a transverse flow eel. The results show that the rate coefficients for the reactions of C2H with propane are independent of temperature while the rate coefficients for the reactions of C2H with isobutane, n-butane, and neopentane have a negative temperature dependence. Over the experimental temperature range, the rate constants for C2H + RH fit the following Arrhenius expressions : k(propane) = (7.8 +/- 0.4) x 10(-11) exp[(3 +/- 12)/T], k(isobutane) = (8.7 +/- 0.8) x 10(-11) exp[(28 +/- 21)/T], k(n-butane) = s(-1). The corresponding rate constants at 298 K are k(propane) = 7.9 x 10(-11), k(isobutane) = 9.6 x 10(-11), k(n-butane) = 1.2 x 10(-10), k(neopentane) = 1.1 X 10(-10) cm(3) molecules(-1) s(-1).