One-step oxidative cleavage of cyclohexene to adipic acid using H2O2 as oxidizing agent and heteropolysalts as heterogeneous catalysts was successfully performed, without the use of additives, such as organic or inorganic acids. The K3PW12O40, K3PMo12O40, Cs3PW12O40 and Cs3PMo12O40 heteropolysalts were synthesized by ion exchange of the respective heteropolyacids using cesium and potassium carbonates. The catalysts were thermally treated at 200 or 600 degrees C and characterized by Raman spectroscopy, thermogravimetric analysis, X-ray fluorescence (XRF) and photoelectronic X-ray spectroscopy (XPS). Raman results showed that the Keggin structure of the polyoxometalates was successfully obtained for both heteropolyacids and heteropolysalts and remained stable even after thermal treatment at 600 degrees C. XRF analysis confirmed the insertion of the cations (Cs+ and K+) into the heteropolysalt structures. All catalysts completely converted cyclohexene within 24 h and they were selective to adipic acid. The best catalyst, K3PW12O40 calcined at 600 degrees C (KPW-600), achieved the highest adipic acid yield (83 %). In this work, we associate the best activity of the KPW-600 heteropolysalt not only to its greater acidity, but also to the higher concentration of (W-O-W)/W species (identified by XPS). Both properties are fundamental for the oxidation reaction of cyclohexene to adipic acid under the experimental conditions used. The results showed that the presence of peroxide species is essential, mainly to favor oxidation reactions, such as the Baeyer-Villiger rearrangement reaction. A reaction scheme for the oxidation of cyclohexene to adipic acid with the best catalyst (KPW-600), was proposed based on our kinetic studies and literature results. In addition to the main mute of adipic acid formation from the direct oxidation of cyclohexene, undesirable parallel reactions of the rearrangement of 1,2 - cyclohexanediol and allyl oxidation were also observed. The influence of reaction conditions was also investigated, as well as the reuse of the most promising catalyst.