[(OEP)As(OH)(2)]ClO4 (4-ClO4) and [(OEP)As(Ph)(OK)]ClO4 (12-ClO4) are synthesized in good yields by oxidative conversion of(OEP)AsCl (2) and (OEP)AsPh (10), respectively, with pyridinium tribromide followed by hydrolysis and counteranion exchange. 4-Cl is converted to [(OEP)As(R)(OH)]ClO4 (6-ClO4, R = Me; 8-ClO4, R = Et) and [(OEP)As(R)(2)]X (7-ClO4, R = Me; 9-PF6, R = Et) by the reaction with (COBr)(2) followed by treatment with trialkylaluminum (alkyl = Me, Et) and counteranion exchange. The reaction of 6-Cl with PCl3 gives the corresponding chloride [(OEP)As(Me)(Cl)]Cl (13-Cl), from which [(OEP)As(Me)(OR)]ClO4 (14-ClO4, R = Me; 15-ClO4, R = Et; 16-ClO4, R = i-Pr), [(OEP)As(Nle)(NH-n-Bu)]ClO4 (17-ClO4>, [(OEP)As(Me)(NH-p-CH3C6H4)]ClO4 (18-ClO4), and [(OEP)As(Me)(Et)]ClO4 (19-ClO4) are synthesized. These compounds are stable toward air and moisture. The OH protons of [(OEP)As(R)(OH)]Cl (6-Cl, R = Me; 8-Cl, R = Et, 12-Cl, R = Ph) are acidic enough to generate [((OEP)As(R)=O)] (20, R = Me; 21, R = Et, 22, R = Ph) by treatment of a solution of 6-Cl, 8-Cl, and 12-Cl with 1,8-diazabicyclo[5,4.0]undec-7-ene (DBU). 6-Cl, 8-Cl, and 12-Cl are regenerated by treating a solution of 20, 21, and 22 with dilute HCl. The first characterization of an arsenic porphyrin 6-ClO4, by X-ray crystallographic analysis is presented.