•A study about authentication of a traditional aniseed flavoured spirit, raki.•Mid-IR spectroscopy is succesfully used in detection of methanol adulteration of raki.•Quantification of adulteration of raki is also achieved with the same technique in combination with chemometrics. Consumption of traditional aniseed alcoholic beverage, raki, adulterated with methanol results in deaths, therefore, its detection is an important issue. In this study, mid-infrared spectra of pure and methanol adulterated (0.5–10% (vol/vol)) raki samples were collected with an attenuated total reflectance attachment of a Fourier-transform infrared spectrometer. Principal component analysis was used to discriminate pure and adulterated raki samples, then, a partial least square model was constructed to determine the adulterant methanol content in raki using mid-IR spectral data. A minimum threshold level of 0.5% methanol in raki samples was successfully detected. A good prediction model for determination of methanol adulteration ratio in raki samples was also constructed (R2=0.98 and RPD=8.35).