In this study, a mordenite-rich tuff (M) from the Sile region (NW Turkey) was treated with HNO3 and H2SO4 at various concentrations (1.0, 3.0 and 5.0 M) at 80 degrees C for 3 h. The adsorption properties of ethylene (C2H4) and hydrogen (H-2) on natural and that of acid forms were examined experimentally at 273 and 77 K and up to 100 kPa using volumetric instrument, respectively. All the samples were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), and nitrogen (N-2) adsorption methods. Some differences on XRD pattern were signed in between natural and acid modified samples according to the intensity, sharpness and crystallite degree of mordenite peaks. C2H4 and H-2 adsorption capacities of the original and acid treated mordenites were in the range of 0.762-0.876 mmol cland 1.373 1.672 mmol g(-1) at 273 and 77 K, respectively. The increasing retention values of C2H4 and H-2 after the acid treatments were analyzed in comparison with the structural changes. (C) 2017 Elsevier Inc. All rights reserved.