The dihalide and pseudohalide radical anions, strong one-electron oxidants, can be selectively generated in aqueous solutions by pulse radiolysis. Radiolysis of salts of the bulky 1-butyl-3-methylimidazolium cation with Cl-, Br-, SCN-, and N-3(-) anions allows efficient generation of the same species (Cl-2(center dot-), Br-2(center dot-), (SCN)(2)(center dot-) and N-6(center dot-) radical anions) also in neat ionic liquids and in nonaqueous solvents with the addition of small amounts of the salt. The oxidative power of dichloride radical anion, lowered in the dichloromethane as compared to the aqueous solution, remains sufficient for oxidation of N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD, (2)k = (2.0 +/- 0.1) x 10(9) M-1 s(-1)), phenothiazine (PZ, (2)k = (2.1 +/- 0.1) x 10(9) M-1 s(-1)), 10-methylphenothiazine (MPZ, (2)k = (9.3 +/- 0.1) x 10(7) M-1 s(-1)), and 3-methylindole (scatole, SCT, (2)k = (6.8 +/- 0.1) x 10(7) M-1 s(-1)). It diminishes on going to Br-2(center dot-) (reacts only with TMPD, (2)k = (5.4 +/- 0.3) x 10(8) M-1 s(-1), and PZ, (2)k = (4.8 +/- 0.3) x 10(8) M-1 s(-1)) while (SCN)(2)(center dot-) and N-6(center dot-) radical anions oxidize only TMPD, (2)k = (5.1 +/- 0.5) x 10(8) M-1 s(-1) and (2)k similar to 10(8) M-1 s(-1), respectively.