The kinetics of the reaction C2H3 + O-2 --> products (reaction 1) has been studied at temperatures 299-1005 K and He densities (3-18) x 10(16) molecule cm(-3) using laser photolysis/photoionization mass spectrometry. Rate constants were determined in time-resolved experiments as a function of temperature and bath gas density. The overall rate constant of reaction 1 is independent of pressure within the experimental range and can be described by the Arrhenius expression k(1) = (6.92 +/- 0.17) x 10(-12) exp((120 +/- 12 K)IT) cm(3) molecule(-1) s(-1). Experimental results are compared with theoretical predictions, and implications for the mechanism of reaction 1 are discussed.