The focus of this research was on effects of temperature, air, nitrogen and vacuum atmospheres effects on structure, reactivity and selectivity of iron-alumina mixed oxides. These composites were prepared by means of sol-gel method using Aluminum iso-propoxide and iron(?) chloride precursors. The characterization of physicochemical properties was carried out using XRD, SEM and FT-IR spectroscopy. To investigate reactivity and selectivity of catalysts, dehydration of 2-octanol and DPP mixture was applied. XRDs pattern indicated in air and vacuum atmosphere,Fe 2 O 3, Al 2 O 3 and Fe 3 O 4 phases and in nitrogen atmosphere Fe 3 O 4 and FeAl 2 O 4 produced respectively. Results indicated that tertiary alcohols adsorb stronger than secondary alcohols over the catalysts surface. This behavior was responsible for the high conversion of DPP vs. 2-octanol over catalysts surface. Besides result of alcohol conversion proved that samples with higher amount of Alumina were more probable absorb of alcohols and in samples with content of Fe 2 O 3 andFe 3 O 4 , higher amount of Fe 3 O 4 was a reason for better absorption on surface of catalysts. One of the most important points in this research was decrease of alcohols conversion percentage with increase of Iron percentage in catalysts content. According to this point the lowest percentage of conversion was related to 100% Fe catalysts. Furthermore, data obtained from distribution of dehydration products indicated that up to 25% Fe, cis-2-octene was the major product in most of catalysts, but from 50% Fe to 100% Fe, 2-octanone was major product. DPP dehydration results analysis indicated that all catalysts produced 1-alkene as major product, except 10% Fe and 50% Fe catalysts which were prepared in air atmosphere that produced E-2-alkene as major product. Maximum of selectivity of 1-alkene obtained from 100% Fe catalysts which were prepared under vacuum atmosphere.