There are disclosed nitric oxide donor compounds of formula (IIa)(see formula IIa)The subject oxide donor compounds show an improved pharmacological profilewith respect tothe known nitric oxide donors. The subject nitric oxide donor compounds areuseful for treatingcardiovascular diseases, inflammation, pain, fever, gastrointestinaldisorders, ophthalmicdiseases, hepatic disorders, renal diseases, respiratory disorders,immunological diseases, bonemetabolism dysfunctions, central and peripheral nervous system diseases,sexual dysfunctions,infectious diseases, for the inhibition of platelet aggregation and plateletadhesion, for treatingpathological conditions resulting from abnormal cell proliferation, vasculardiseases. Theinvention also relates to pharmaceutical compositions comprising at least onenitric oxidereleasing compounds.