A process for the polymerization of formaldehyde, comprising contacting formaldehyde in a hydrocarbon solution with an aliphatic anhydride and a quaternary ammonium salt polymerization initiator of the formula: R.sup.1R.sup.2R.sup.3R.sup.4N.sup.+X.sup.- where R.sup.1 is an aliphatic or olefinic hydrocarbon group containing about 18 to about 25 carbon atoms; R.sup.2, R.sup.3, and R.sup.4 are each methyl, ethyl, and/or propyl, such that the total number of carbon atoms in R.sup.2, R.sup.3, and R.sup.4 combined is between 3 and 7; and X.sup.- is an organic anion.