The removal of formaldehyde from aqueous solutions of 2-butyne-1,4-diol (ED), which are prepared from ethynylation of acetylene with aqueous formaldehyde, was successfully accomplished by a number of approaches: reaction with sodium bisulfite and removal of the resultant ionic product with an anion exchange resin in a fixed bed system or using an anion exchange resin bed in bisulfite form; reactive distillation with methanol and ethylene glycol in the presence of cation exchange resin as catalyst to give the corresponding acetals; internal acetalization with ED in the presence of cation exchange resin as catalyst; Cannizzaro＇s reaction with sodium hydroxide; and aldol type condensation in the presence of sodium hydroxide. Residual concentrations of formaldehyde as low as 20 ppm could be achieved through more than one of the methods mentioned above.