A process for preparing predominantly noncyclic polyalkylene polyamine compounds is disclosed wherein an alkanolamine compound and an alkyleneamine compound in a molar ratio of alkanolamine compound:alkyleneamine compound of 1:5 to 3:1, preferably less than 1, is reacted in the presence of a catalytically effective amount of a Group IIA or Group IIIB metal acid phosphate at a temperature from about 200.degree. to 400.degree. C. under a pressure sufficient to maintain the reaction mixture substantially in liquid phase.