The general synthesis, isolation and characterization of electrophilic iodine reagents of the general formula R₄N[I(O₂CAr)₂] is reported. These compounds are air- and moisture-stable iodine(I) reagents, which were characterized including X-ray analysis. They represent conceptually new iodine(I) reagents with anions as stabilizers. These compounds display the expected performance as electrophilic reagents upon interaction with electron-rich substrates. The performance of these compounds in a total of 47 different reactions of vicinal iodooxygenation of alkenes is studied and some key features on the reagents are revealed.