Disclosed are methods and apparatus enabling the efficient utilization of urea for purposes such as selective catalytic reduction (SCR) of NOx, which enable feeding urea to a chamber designed to efficiently and completely gasify the urea to enable ammonia feed. Preferably, aqueous urea is fed to a gasification chamber, which is also fed with heated gases. An injector means, capable of distributing the aqueous urea as fine droplets, is positioned centrally of a gas distribution plate in the chamber. An arrangement of spaced holes in the gas distribution plate provides higher gas velocity in the vicinity of the injector means than near the walls of the chamber. Uniform gas distribution without equipment fouling is achieved.