4-acetamido-TEMPO (short for (4-acetamido-2,2,6,6-tetramethylpiperidin-1-yl)oxyl) is a stable radical used for oxidation reactions in organic chemistry.

Oxidation to the nitroxyl radical occurs with hydrogen peroxide in the presence of sodium tungstate and ethylenediaminetetraacetic acid.

[1] 4-acetamido-TEMPO is a stable radical and exists as a crystalline, orange-colored solid.

[1] A closely related reagent is the Bobbitt's salt, an oxidized derivative of 4-acetamido-TEMPO.

[2] The Bobbitt salt can be prepared starting from 4-acetamido-TEMPO by reacting it first with tetrafluoroboric acid and then with sodium hypochlorite.