Deaths related to carbon monoxide (CO) poisoning are common. Most represent accidents and suicides, and most result from CO production via the incomplete combustion of carbon-containing substances. Suicide via CO toxicity is not uncommon and typically involves the use of motor-vehicle exhaust as a source of CO. Presented herein is a case of suicidal CO poisoning in which the CO was produced via a chemical reaction between formic acid and sulfuric acid within a homemade device.