The increasing use of synthetic dyes in commercial food processing has heightened the need for more effective methods of treating industrial wastewaters prior to discharge into the environment. The present report describes the efficient electrodegradation of tartrazine dye in dilute aqueous solution using the electro-Fenton process with Fe (II) or Fe (III) as catalyst and a gas diffusion electrode modified with 5.0% cobalt phthalocyanine. The highest level of color removal (98.4% in 90 min) from solution and the most rapid decay in concentration (k(app) 6.0 x 10(-2) min(-1)) of tartrazine dye were achieved in the presence of 0.15 mmol Fe (II). Under these conditions, the amount of total organic carbon (TOC) removed in 90 min was maximal (75%) while energy consumed was minimal (219.0 kWh kg(-1) TOC removed). The amount of residual iron was slightly higher than that allowed by the Brazilian authorities for dissolved Fe in wastewaters, indicating that further treatment of the effluent would be necessary. (C) 2014 The Electrochemical Society. All rights reserved.