Abstract: A fuel vaporizing and atomizing device which is particularly suitable for ammoniacal fuels comprises a chamber having a resonant plate therein, possibly forming part or all of one wall of the chamber, which plate is in physical contact with a transducer operating to vibrate the plate at an ultrasonic frequency in order to encourage vaporization which is further enhanced by passing the partly vaporized fuel through a silent discharge device operating at a very high voltage, following which the fuel passes over a catalyst such as platinum.