This paper sums up all the different steps broached in this project : The NIR spectroscopy technique has been studied and implemented at CTP using a mobile spectrometer device and different optical materials. Methods, based on statistical data analysis (in particular PLS regressions), have been investigated. A laboratory "prototype" using these techniques and methods has been developed in order to control the recovered papers quality, in terms of humidity percentage and sample composition (paper, board, contaminants).