Methane chloride (CH3Cl) in syngas is able to suppress the phosphine (PH3) poisoning effects on a solid oxide fuel cell under various conditions. The mechanism is revealed by combining a thermodynamic analysis and a study of P-Cl chemisorption at nickel surface. The resulting negative Gibbs energy is favorable to reactions between gaseous phosphorus (considered to be P-2) and CH3Cl, predicting the generation of phosphorus trichloride (PCl3). However, the binding energies between P/Cl and nickel show that the PCl3 formed is not stable, so chlorine combined with P under these conditions at nickel surface is therefore expected to inhibit passivation by phosphorus. (C) 2015 Elsevier Ltd. All rights reserved.