The use of nanofilled polymers in polymer science has developed rapidly over the last years. Thereby it is essential to reach a homogeneous dispersion of the nanoscale filler (especially layered silicates) and to observe the homogeneity of the nanoparticles. An in-line characterization during processing is most efficient to ensure a constant high quality. The goal of this diploma thesis is to implement an in-line near-infrared (NIR) system on a co-rotating twin-screw extruder, to characterize the nanoparticles. In Addition the theoretical background of the NIR-technology including the functionality of chemometrics, spectral pretreatment, the state of technology and the versatile capabilities and capacity of a NIR-spectrometer are explained in this thesis. The polypropylene HC600TF of Borealis Inc. and the organoclay Nanofil 5 of Südchemie Inc. were processed in a TSK 30/40D twin screw compounder (Theysohn Inc.) with a melt pump and two different extruder geometries. For the on-line measurement of the drawing force the rheotens equipment 71.97 of Göttfert Werktstoff-Prüfmaschinen Inc. was used. NIR- and rheotens measurements were done simultaneously during the processing of the nanocomposites near the end of the tie. The measured values of the drawing force were used as reference values for the generation of the chemometric models. The generated models were judged through the correlation parameters R (coefficient of determination) and RMSECV (Root Mean Square Error of Crossvalidation). The calculated models had a coefficient of determination of 94.6% and 97.6% resp. with a RMSECV of 2.64 mN and 1.98 mN respectively. Furthermore a geometry-independent model was created which reached a superb correlation with R = 95.6% and a RMSECV of 2.22 mN. This thesis demonstrates that the NIR-technology is perfectly suitable for in-line characterization. The results show that it is possible, through the installation of a NIR-spectroscope on a nanocomposite-processing compounder, to optimize the process of compounding in terms of increased and constant quality. This will accelerate research on this sector and would create a considerable advantage in regards of new processing technologies.