A high resolution near infrared (NIR) diode laser spectrometer along with a multipass cell is used to detect weak rovibronic transitions of carbon dioxide in the NIR region. The self, nitrogen and air broadening line shape parameters of three rovibrational transitions P(44), P(46) and P(48) of 12C 16O 2 belonging to the (ν 1+5 ν 3) overtone band around 780 nm are studied.Wavelength modulation spectroscopy with phase sensitive detection technique at the first harmonic is used to detect the weak overtone transitions of CO 2. The observed line shapes are fitted with the standard Voigt profile by a non-linear least squares fitting program in order to determine the self and buffer gas (air and N 2) broadening coefficients and line strength parameters of the CO 2 transitions. The O 2 broadening coefficients are calculated from the experimentally measured N 2 and air broadening coefficient values. The measured parameters are compared with the available experimental data and a reasonable agreement has been found. © EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2012.