We report for the first time the effect of clinoptilolite dealumination on the propane-SCR-NOx process. This has been accomplished using a mild acid like oxalic acid to avoid excess catalyst crystallinity deterioration. It had been shown that dealumination may result in a significant enhancement of NOx conversion to N-2 when an optimum acid concentration of 0.050 M is used for a treatment period of 2 h. Dealumination substantially affects the distribution of the concentration of acid sites of different strength. The effect of dealumination on the HC-SCR activity of the zeolite samples is discussed in terms of Si/Al ratio, crystallinity, distribution of acid site strength, extra framework species concentration and textural characteristics of the samples. (C) 2014 Elsevier B.V. All rights reserved.