The kinetics of the reaction B(P-2(J)) + C2H4 has been investigated between 23 and 295 K in a continuous flow CRESU (cinetique de reaction en ecoulement supersonique uniforme) apparatus using pulsed laser photolysis of trimethyl borate, B (OCH3)(3), to generate B(P-2(J)) atoms and laser-induced fluorescence to observe the kinetic decay of the boron atoms and hence determine the rate coefficients. The thermal rate constant temperature dependency is well described by the following expression: k(T) = (1.86 +/- 0.40) x 10(-10) (T/300)(-(0.70+/-0.30)) x exp(-(26 +/- 14)/T) cm(3) molecule(-1) s(-1) indicating the absence of any significant activation barrier in the entrance channel of the potential energy surface of the title reaction.