A one-pot synthesis of (+)-3-[C-11]cyano-MK-801 was performed using a palladium-promoted reaction of hydrogen [C-11]cyanide with (+)-3-iodo-MK-801. The synthesis time was 32 min counted from end of bombardment, affording (+)-3-[C-11]cyano-MK-801 in 37 % decay-corrected radiochemical yield based on hydrogen [C-11]cyanide. The radiochemical purity was higher than 95 % and the specific radioactivity was in the range of 220-600 GBq/mu mol. In vitro investigations in homogenate and frozen sections of rat brain indicated that (+)-3-[C-11]cyano-MK-801 may be used as tracer in studies of the NMDA receptor.