A nitric oxide delivery device comprising an enclosure, said enclosure forming or containing: a first compartment containing an amount of a reducing agent and an amount of an agent capable of forming a transient complex with nitric oxide; a second compartment containing an amount of a nitric oxide precursor that forms nitric oxide when contacted with and reduced by the reducing agent; a barrier separating the contents of the first and second compartments wherein: said enclosure comprises a nitric oxide-permeable membrane that is impermeable to the nitric oxide precursor, the agent capable of forming a transient complex with nitric oxide, and the reducing agent: at least one of the first compartment and the second compartment contains water; the first and second compartments are configured such that breaking or removing the barrier allows the nitric oxide precursor to mix with the reducing agent and complex forming agent, thereby producing an aqueous nitric oxide producing mixture containing a transient nitrosyl complex; the agent capable of forming a nitrosyl complex and the nitric oxide precursor are present in the device in a molar ratio in the range of from 1.5:1 to 10:1; the reducing agent or agent capable of forming a nitrosyl complex or both are selected from the group comprising Fe, and salts thereof; and said transient nitrosyl complex is arranged in said device to delay the release of NO from the device through the nitric oxide-permeable membrane. a first compartment containing an amount of a reducing agent and an amount of an agent capable of forming a transient complex with nitric oxide; a second compartment containing an amount of a nitric oxide precursor that forms nitric oxide when contacted with and reduced by the reducing agent; a barrier separating the contents of the first and second compartments wherein: said enclosure comprises a nitric oxide-permeable membrane that is impermeable to the nitric oxide precursor, the agent capable of forming a transient complex with nitric oxide, and the reducing agent: at least one of the first compartment and the second compartment contains water; the first and second compartments are configured such that breaking or removing the barrier allows the nitric oxide precursor to mix with the reducing agent and complex forming agent, thereby producing an aqueous nitric oxide producing mixture containing a transient nitrosyl complex; the agent capable of forming a nitrosyl complex and the nitric oxide precursor are present in the device in a molar ratio in the range of from 1.5:1 to 10:1; the reducing agent or agent capable of forming a nitrosyl complex or both are selected from the group comprising Fe, and salts thereof; and said transient nitrosyl complex is arranged in said device to delay the release of NO from the device through the nitric oxide-permeable membrane. said enclosure comprises a nitric oxide-permeable membrane that is impermeable to the nitric oxide precursor, the agent capable of forming a transient complex with nitric oxide, and the reducing agent: at least one of the first compartment and the second compartment contains water; the first and second compartments are configured such that breaking or removing the barrier allows the nitric oxide precursor to mix with the reducing agent and complex forming agent, thereby producing an aqueous nitric oxide producing mixture containing a transient nitrosyl complex; the agent capable of forming a nitrosyl complex and the nitric oxide precursor are present in the device in a molar ratio in the range of from 1.5:1 to 10:1; the reducing agent or agent capable of forming a nitrosyl complex or both are selected from the group comprising Fe, and salts thereof; and said transient nitrosyl complex is arranged in said device to delay the release of NO from the device through the nitric oxide-permeable membrane. at least one of the first compartment and the second compartment contains water; the first and second compartments are configured such that breaking or removing the barrier allows the nitric oxide precursor to mix with the reducing agent and complex forming agent, thereby producing an aqueous nitric oxide producing mixture containing a transient nitrosyl complex; the agent capable of forming a nitrosyl complex and the nitric oxide precursor are present in the device in a molar ratio in the range of from 1.5:1 to 10:1; the reducing agent or agent capable of forming a nitrosyl complex or both are selected from the group comprising Fe, and salts thereof; and said transient nitrosyl complex is arranged in said device to delay the release of NO from the device through the nitric oxide-permeable membrane.