The nitric oxide (NO) removal capacity of ion-exchanged zeolite Y obtained from coal combustion fly ash was evaluated in this work. Zeolite Y was exchanged either with Cu2+ or Fe2+ to obtain two different catalysts for the selective catalytic reduction of NOx from flue gas. The selective catalytic reduction experiments were carried out at temperatures ranging from 50 degrees C to 350 degrees C, water content 0% and 5% and 5% O-2. In the absence of water, a total conversion of NO is obtained at 200 degrees C for both zeolites, but important differences were found between zeolites LY-Cu and LY-Fe in the reduction of NO at temperatures lower than 200 degrees C, and especially in the presence of water, that could be attributed to the different temperatures at which active species Cu2+ and Fe3+ are available for both ion-exchanged zeolites at the studied conditions. The greater surface area of zeolite LY-Cu can also contribute to its higher activity.