The influence of Cr2O3 on properties of the Cr2O3/MgF2 catalysts obtained by impregnation and precipitation-deposition is described. The IR technique enabled monitoring of changes in the structure of the MgF2 surface after introducing chromium ions. Tetrahedral chromium complexes as well as structures of Cr2O3 type were observed. The deposited species generated the Lewis and Bronsted acidity which in turn was responsible for the catalytic activity in the reactions of 2-propanol decomposition, butene double bond isomerization, cumene cracking, dehydrogenation of cyclohexane and decomposition of methyl alcohol.