Sulfated mixed oxides, SO4=/Ni-Al-O and SO4=/Zr-Al-O were evaluated for double bond isomerization (DBI) of 1-hexene using helium and hydrogen as carrier gases. The increase of temperature from 100 to 200 degrees C seems to favor the deprotonation pathway and contribute to increase the 1-hexene conversion for both catalysts and without regard of the carrier gas. The results indicate that temperature it is the main factor that contributes to improve both conversion and selectivity towards (cis + trans)-2-hexene, while the reductive atmosphere beneficiate only the SO4=/Ni-Al-O catalyst performance, as hydrogen prevents this catalyst from a fast deactivation.