Abstract Observations of the 10 488-Å band of carbon dioxide in the spectrum of Venus were made from January, 1965 through December, 1967. The spectra were obtained at the coudé focus of the Struve reflector at dispersions of 2.8, 3.8, and 5.4 Å/mm. The 31 best plates were used to derive rotational temperatures by two methods. In the first method we made linear least-squares fits to a square-root absorption law and derived temperatures ranging from 193° to 284°K, with an average temperature of 244°K. The second method also required a linear least-squares fit, this time to the curve of growth. This fit gave slopes from 0.38 to 0.58, corresponding to rotational temperatures of from 202° to 250°K, with an average temperature of 236°K. The rotational temperatures derived by both methods showed no significant variation with the phase angle, i, of Venus, for 26° ≤ i ≤ 164°. Finally, averaging the measurements obtained by three individuals and using the curve of growth method of data reduction, gives T rot = 237° ± 3°K (formal standard deviation). We searched for spatial and temporal variations in the apparent amount of carbon dioxide in the absorption path. The amount appeared to vary significantly with the phase of Venus and also with the time of observation.