The aim of this work was to predict composition and nine selected physicochemical properties of fossil/synthetic aviation fuel blends by chemometric analysis of mid-infrared spectra. Therefore, infrared spectra of various mixtures with six different synthetic hydrocarbon fuels were recorded and comprehensively interpreted, supported by data from comprehensive two-dimensional gas chromatography mass spectrometry analysis of these fuels. Deep insight has been gained on how individual blend components are differentiated in principal component analysis and how they influence physicochemical properties by means of partial least squares regression. A chemometric model has been established to determine the amount of an individual synthetic fuel in a blend with a precision of <1 vol % and a detection limit of <2 vol %. The quality of prediction of physicochemical properties is good enough to compete with results obtained by established test methods.