The temperature dependence of the overall rate constant for the C2H5O2 + NO reaction and the rate constant for the minor branching channel resulting in the production of C2H5ONO2 have been measured using the turbulent flow technique with high-pressure chemical ionization mass spectrometry for the detection of reactants and products. The temperature dependence of the overall rate constant for the C2H5O2 + NO reaction was investigated between 299 and 213 K at 100 Torr pressure, and the data was fit to the following Arrhenius expression (with 2 standard deviation error limits indicated): 3.8(-1.3)(+2.1) x 10(-12)exp[(290 +/- 110)/T] cm(3) molecule(-1) s(-1). The temperature dependence of the overall rate constant agrees well with the current recommendation for atmospheric modeling. The minor reaction channel C2H5O2 + NO - C2H5ONO2 was directly observed for the first time, and the temperature dependence of the rate constant for this channel was investigated between 298 and 213 K at 100 Torr pressure. The following Arrhenius expression was determined for the minor channel: 1.6(-1.2)(+4.0) x 10(-15)exp[(1160 +/- 310)/T] cm(3) molecue(-1) s(-1). The Arrhenius expressions for the overall rate and the C2H5ONO2 producing channel indicate a branching ratio of about 0.006 at 298 K and 0.02 at 213 K at 100 Torr pressure. The temperature dependence of the overall rate constant for the C2H5O2 + NO2 reaction was also investigated between 299 and 213 K at 100 Torr pressure, and the data was fit to the following Arrhenius expression: 4.7(+2.0)(-1.4) x 10(-13)exp[(620 +/-89)/T] cm(3) molecule(-1) s(-1).