The quality, safety and authenticity of food are of principle interest for society and are regulated by legislation. Due to their high market value, meat and fish products are often targets for species substitution and adulteration. Testing food is one of the key ways of checking whether food businesses are complying with food law. But the current methods used for determination of species and adulteration (e.g. ELISA) are time consuming, can be costly and typically located in a laboratory some distance from the producer and retailer. Rapid Evaporative Ionisation Mass Spectrometry (REIMS) combined with multivariate statistical analysis (Principal Component Analysis and Linear Discriminate Analysis) is an emerging technique for near real time characterization of tissues with no requirement for sample preparation. We introduce that REIMS is able to differentiate meat and fish samples originating from different species, regardless of which tissue is chosen.