Alkylene oxide adducts of higher alkanols are prepared by a process which comprises contacting and reacting an alkylene oxide reactant comprising one or more C.sub.2 to C.sub.4 vicinal alkylene oxides with an alkanol reactant comprising one or more C.sub.6 to C.sub.30 alkanols in the presence of a catalytically effective amount of a catalyst which combines (i) one or more phosphorus-containing acids with (ii) one or more aluminum compounds selected from the group consisting of aluminum alcoholates and aluminum phenolates, the relative molar ratio of component (i) to component (ii) being in the range from about 0.1:1 to 2.5:1. Alkanol alkoxylates, and particularly alkanol ethoxylates, prepared in this manner are characterized by a relatively narrow-range distribution of alkylene oxide adducts and by a relatively low content of residual alkanol. The products of this process are nonionic surfactants, particularly useful as components of detergent formulations.