Spectral raw data from the TreeTalker device are output as radiometrically uncalibrated and with the 12 different spectral bands not directly comparable among each other, hence hindering the retrieval of the real spectral signature from the observations. This report describes the methodology and results of experiments aimed at obtaining custom calibration factors to convert the raw data output from the TreeTalker spectrometer into values of radiative energy flux for each spectral band.