[en] Highlights: • Industrial phosphoric acid is less aggressive than simulated industrial acid. • Polyphosphate film in Industrial acid is reinforced by calcium and sulfate. • Passive film thickness is obtained by the power law model from EIS measurements. • Passive film of Sanicro28 becomes more resistive towards corrosion with exposure time in industrial acid. • XPS measurements coupled to Raman spectroscopy reveal the corrosion products formed in simulated acid. - Abstract: The corrosion behaviour of Sanicro28, in industrial phosphoric acid and simplified solution of pure H_3PO_4 containing sulphates and chlorides, is investigated during 48 h between 20 and 80 °C. Results show higher corrosion resistance in the industrial medium. Film thickness evaluated by EIS remains constant in industrial acid due to polyphosphate that promotes crystallisation of the Cr_2O_3 inner layer. Conversely, the passive film is partially destroyed at 80 °C in simplified acid. XPS and Raman analysis show that phosphate and molybdenum are both present in the passive film and in corrosion products. The role of Ca present in the industrial acid is discussed.