24 healthy young men were exposed for 30 min to GSM-handset-like (PM) or continuous-wave (CW) RF EMF (900 MHz; peak specific absorption rate 1W/kg), or sham exposed. During exposure, participants performed cognitive tasks. Waking electroencephalogram was recorded during baseline, immediately after, and 30 and 60 min after exposure. Pulse-modulated radio frequency electromagnetic field exposure reduced reaction speed and increased accuracy in a working-memory task. It also increased spectral power in the waking electroencephalogram in the 10.5--11 Hz range 30 min after exposure. No effects were observed for CW exposure.