2-Oxyhydrazino-N-(2-methylen-yl-hydroxyphenyl)pyridinium (OMHP) ion was immobilized onto Na-montmorillonite clay (MMT). The modified clay (OMHP-MMT) was used for the removal of Cu(II). Experiments were carried out as a function of solution pH, stirring time, effect of some common ions and eluent type, concentration and volume. MMT. OMHP-MMT, and OMHP-MMT-loaded Cu(II) were characterized by X-ray diffractometry, electronic and infrared spectra, and elemental and thermogravimetric analyses. OMHP is suggested to be intercalated into MMT parallel to the aluminosilicate layers, with a capacity of 56.4 mEq/100 g. OMHP-MMT shows good stability in 0.1-1 mol L-1 hydrochloric or nitric acids, ammonia hydroxide, concentrated Na+, K+, NH4+, Cl- or SO42-. It shows good removal efficiency and selectivity towards Cu(II) at pH 3.0-8.0 and stirring time 10 min with an removal capacity of 119 mEq/100 g. Most common ions do not interfere with the removal process except Fe3+. Extracted Cu(II) could be quantitatively recovered by 10 mL 1% thiourea in 0.1 mol L-1 HCl with 100-fold preconcentration factor. OMHP-MMT was successfully applied to recover Cu(II) from different samples. (C) 2010 Elsevier B.V. All rights reserved.