Direct measurements were made of the temperature dependence of the photolysis rate coefficient of NO2 (j1) at temperatures from -70¿ to 30≡ in sunlight for relatively cloudless summer days in Boulder, Colorado. The ratio of the j1 values (j1(30¿C)/j1(T¿C) for T=-20¿ and 70¿C are, respectively: 1.046¿0.040 and 1.070¿0.31 (95% confidence limits). The j1 ratios were independent of solar zenith angle (22¿<Z<47¿). Theoretical estimates of the temperature dependent j1 ratios based upon recently reported cross section (&sgr;) and quantum yield (ϕ) data are more consistent with these experimental measurements than those based upon the currently accepted &sgr; and ϕ data. ¿ American Geophysical Union 1988