Abstract: An improvement for manufacturing paraformaldehyde prills from an aqueous solution of formaldehyde which comprises polymerizing the formaldehyde in the presence of a catalyst of sodium hydroxide in a concentration of from about 0.5 to about 5 ppm, aging the resulting mixture at about 100.degree. to about 130.degree. C. for about 10 to about 60 minutes, spraying the aged mixture into a prilling tower at from about 100.degree. to about 130.degree. C., collecting the prills in a fluidized bed at the base of the tower at from about 45.degree. to about 60.degree. C., removing the prills to a separate vessel where the prills further polymerize and dry at from about 15.degree. to about 30.degree. C. for about 3 to about 5 hours while operating the vessel in a plugged flow manner, and collecting the resulting prills.