Silica-supported copper (Cu/SiO2) catalysts were prepared by impregnation assisted with organic additives and employed as an efficient catalyst for oxidant-free vapor-phase dehydrogenation of 1-decanol to decanal. The XRD, N2O titration, and TEM analyses showed that the utilization of organic additives generated Cu/SiO2 catalysts with better Cu dispersion and smaller particle sizes, which led to a significantly larger Cu surface area than the Cu catalyst prepared without organic additives. Among several additives-assisted Cu/SiO2 catalysts tested, the Cu/SiO2 assisted with the 12-crown-4-ether (12C4) gave the highest catalytic performance for dehydrogenation of 1-decanol to decanal. Compared to the unassisted Cu/SiO2 catalyst, the Cu catalyst prepared with 12C4 had a higher formation rate with significantly better long-run performance. The dehydrogenation activity, i.e. the formation rate of decanal, was simply proportional to the copper surface area of catalysts.