This paper investigates the effect of the equivalence ratio Phi and ignition advance angle theta(i) on idle characteristics of a turbocharged hydrogen fueled SI engine. The experimental data was conducted under various operating conditions including different Phi and theta(i) It is found that, the ignition advance angle at MBT point decreases gradually with the equivalence ratio increasing from 0.4 to 0.9. Indicated thermal efficiency decreases as Phi increases. Emissions of NOx increase as Phi increases. When Phi is kept constant, the stated emissions increase as theta(i) increases. During idle conditions of a hydrogen fueled engine, a lean mixture with an Phi less than 0.4 is suitable, and the theta(i) should be increased appropriately. The maximum cylinder pressure rises with an increase of Phi and theta(i). The trend of the maximum rate of pressure rise is similar at different Phi. Only under the conditions of Phi = 0.4 and theta(i) < 10 degrees CA, the maximum pressure rise rate remains almost unchanged. Copyright (C) 2010, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.