This study compares the performance of radiative transfer model inversion techniques to estimate leaf chlorophyll content (LCC) from summer barley based on hyperspectral data. The PROSAIL model was used to simulate vegetation reflectances. Model performance was tested against 168 ASD measurements taken under controlled conditions in an experimental station. An iterative optimization technique (IO), a look-up table (LUT) and a support vector regression (SVR) were applied to invert the PROSAIL model. A new and efficient method for LUT generation is presented which serves also as an extensive data basis to train the SVR. Highest accuracy for LCC estimation was achieved with the IO (R2=0.72). The performance dropped to R2=0.51 using the LUT but improved when the same dataset was used to apply the machine learning technique (R2 for SVR=0.67).