Abstract: A method of breaking crude oil emulsions using a water-in-oil emulsion breaker obtained by the reaction, in anhydrous conditions, for at least one hour, of an alkyl substituted phenol-formaldehyde polymer having the structure: ##STR1## wherein R is a linear or branched alkyl group having from 4-20 carbon atoms, and wherein m and n are both independent integers, the sum of which is sufficient to achieve a molecular weight of at least 1000 and further that m, but not n, may be zero with (b) ethylene carbonate, said reaction being further accomplished in a common oleophilic solvent having a boiling point of at least 180.degree. C., the reaction further at a temperature of at least 160.degree. C. in the presence of an alkaline catalyst, said catalyst being present at a concentration, based on total weight of reactants a & b, of at least about 0.1 weight percent.