An oxygen-absorbing composition including iron and a soluble tartrate. A method of absorbing oxygen from a closed environment including the steps of providing an oxygen-absorbing composition containing iron and a tartrate, injecting water into the composition, and placing the composition into the closed environment. An oxygen-absorbing packet containing iron and a tartrate. All of the foregoing-mentioned compositions preferably include an electrolyte. The tartrates may be selected from the group which may include sodium acid tartrate, potassium acid tartrate, potassium sodium tartrate tetrahydrate and sodium tartrate dihydrate, but are not limited thereto.