Magnesia-supported platinum-tin catalysts with a Pt content 0.25-3% and atomic ratio Pt/Sn = 1 were prepared from a Pt-Sn bimetallic complex. Characterization of catalysts by XRD, TEM, EDX, XPS and CO singleton frequency indicated the formation of well-dispersed bimetallic particles, the size of which decreased with the metal content. Both dilution and electronic effects on Pt by Sn were evidenced by IR experiments of CO adsorption. The behavior of catalysts in isobutane dehydrogenation at 753 K and atmospheric pressure was related to their structural characteristics and compared to silica- and alumina-supported catalysts prepared by a similar method, and to the respective monometallic catalysts. Magnesia-supported bimetallic catalysts were the most selective to isobutene production. Selectivities higher than 99 % were achieved for conversion values of 11%.