Abstract: A method and composition are disclosed for sweetening, i.e., selectively reducing the levels of H.sub.2 S and organic sulfides, in gaseous hydrocarbons streams, particularly natural gas streams. A natural gas in a pipe line, at the well head, or at a common collection point from a number of wells, is contacted with a sweetening agent comprising the reaction product of ethylene diamine with 50% uninhibited aqueous formaldehyde. The reaction product is prepared by reacting one part 99% ethylene diamine with two parts 50% aqueous uninhibited formalin at a temperature of about 55-60.degree. C. (higher temperatures may be used if the reaction is carried out under pressure) and is characterized by having a higher flash point, lower toxicity, and a lower freezing point, and better reaction rates, than other sweetening agents currently in use.