The work focuses on the glycerol acetylation to triacetin over solid acid catalysts in liquid and gas phase. Acidic catalysts such as ion-exchange resins and supported heteropolyacids (HPA) were studied using toluene as an entrainer in batch-liquid phase. The high activity of catalysts depends on acidity and Keggin structure stabilization on the support. Low acidic catalysts like SiO2-based mixed metal oxides (TiO2, MgO, ZrO2, SrO and Sc2O3) were evaluated in continuous-gas phase. The high activity of SiO2-TiO2 catalyst seems to be related to the formation of Si-O-Ti bonds within the SiO2.