Apparatus producing superheated water and/or steam for weed (36) killing, etc.has diesel fired boiler (30), which, via pump (32), generates hot water at apressure of 40-52 bar and temperature of 90-115~ C. This passes down tube (12)and encounters the constriction provided by nozzle (14). Passing throughnozzle (14) into depressurisation chamber (16), which is at atmosphericpressure, the water boils. When the super heated water exits ports (20) ofdistribution pipe (18) it encounters ambient temperature and is transformedinto high temperature water vapour and/or water droplets. The apparatuscontrols or kill weeds (36) using a smaller volume of water and less energy.
