The amount and nature of carbon deposits on platinum catalysts supported on a mixture of alumina-beta-zeolite, non neutralized and neutralized with cesium, were investigated and compared with those of a commercial catalyst (Pt/Al2O3). The catalysts were deactivated in the methylcyclopentane reaction. Coke characterization was performed by elemental analysis, temperature-programmed oxidation (TPO), Fourier transform infrared (FTIR), and C-13 (CP/MAS) NMR. The significant difference between Pt/Al2O3 and Pt supported on a mixture of gamma-alumina and beta-zeolite is the nature of the carbon deposits. Elemental analysis, TPO, FTIR, and C-13 (CP/MAS) NMR pointed out different features of the deposits. The zeolitic catalyst neutralized by Cs presented similar amounts of carbon residues but was the most deactivated. The results point out acid sites with different responses to carbonaceous residues.