(OEP)Os(CO) reacts with n-butyl nitrite to give, after workup, the (OEP)Os(NO)(O-n-Bu) trans addition product (OEP = octaethylporphyrinato dianion). Similarly, the reaction of (OEP)Os(CO) or [(OEP)Os](2) with isoamyl nitrite gives the corresponding nitrosyl alkoxide, (OEP)Os(NO)(O-i-C5H11). The related reactions of (OEP)Os(CO) or [(OEP)Os](2) with isoamyl thionitrite gives the (OEP)Os(NO)(S-i-C5H11) nitrosyl thiolate. The reaction of the [(OEP)Os](2)(PF6)(2) reagent with isoamyl thionitrite gives the nitrosylation product, [(OEP)Os(NO)]PF6, which undergoes anion hydrolysis to give the isolable difluorophosphate (OEP)Os(NO)(O2PF2) derivative. Interestingly, the reaction of O2NC6H4N=NSPh with [(OEP)Os](2) gives the (OEP)Os(SPh)(2) product with loss of the arylazo fragments. The solid-state structures of (OEP)Os(NO)(O-n-Bu), (OEP)Os(NO)(O2PF2), and (OEP)Os(SPh)(2) have been determined by X-ray crystallography.