Optical spectroscopy is investigated with respect to its capabilities to yield temperature information from line intensities of low temperature plasmas. The method is non‐invasive and easy to perform experimentally. The data analysis model consists of a population model describing the intensities of light emission. Geometry effects and measurement errors are encountered. The quantity of interest is the electron energy distribution function. A Bayesian framework was chosen to incorporate systematic uncertainties and to incorporate physics information coherently. As an example, results from in‐situ wavelength calibrations are discussed. Sensitivity studies of modeled spectra are outlined.