Two new nanostructured Al2O3 - ZrO2 mixed oxides supports, A and B, have been prepared by sol - gel process and characterized by TEM, XRD and XPS methods. The freeze-dried gel gave support A whereas the support B was obtained by drying of gel at ambient temperature. Both supports reacted with Rh(acac)(CO)(2) complex, producing Rh(CO)(2)(+) tethered species, characterized by v(CO) at 2011 and 2083 cm(-1). The Rh(CO)(2)(+) /A applied as catalyst for reaction of 1-hexene at 80 degreesC with H-2/CO = 1, at 10 atm was found as active for isomerization (ca. 90% of 2-hexene after 6 h) and relatively poor catalyst of hydroformylation (< 10% of aldehydes). At the presence of stoichiometric amount of PPh3 the yield of aldehydes increased up to 65%. The selectivity of the reaction was strongly dependent on the catalyst pre-treatment with CO or CO/H-2 mixture.