Abstract4‐[82Br]Bromoantipyrine has been synthesized by three methods:the melt method, the isotopic exchange in acidic medium method and the silica gel catalyzed method. The melt method is the simplest one and gives the highest radiochemical yield (∼ 90%). 4‐[131I]‐Iodoantipyrine has also been synthesized by these three methods with higher radiochemical yield than the bromo analog. The radiochemical yield of 4‐[131I]iodoantipyrine synthesized by the silica gel catalyzed method depends on the reaction time of antipyrine with [131I]NaI solution, but does not depend largely on the contact time between antipyrine‐[131I]NaI solution with silica gel. I2or I+was proposed as an intermediate for this reaction.The mean octanol/pH 7 buffer solution partition coefficient of 4‐[82Br]bromoantip