Dyes are pollutants resulted from the textile, paper, and leather industries, are considered sources of environmental contamination. This study is devoted to utilize a low-cost modified local natural source, for removing the Malachite Green cationic dye (MG) from aqueous solution. Zeolite-A (ZA) was prepared in a good Crystallinity via hydrothermal heating from local kaolin at mild conditions. The mineralogical, structural, and chemical properties of both, the precursor rock and ZA that formed were identified via X-ray Diffraction (XRD), scanning electron microscope (SEM), and X-Ray Fluorescence (XRF) techniques. To identify the impact of operational parameters, a series of adsorption studies were performed, such as initial concentration, pH, adsorbent dose, initial dyes concentration, contact time, ionic strength and temperature on the complete dye removal. The thermodynamic parameters (ΔH, ΔS and ΔG) of adsorption systems were also determined and evaluated. The resulting degrees of dye removal were 59–86.5% for initial dye concentration of 10 mg/L and for ZA loadings of 0.01–1.00 g. It was found that the adsorption of MG on ZA followed a pseudo-second order model, the data proved well fitted to the Langmuir isotherm model and thermodynamic studies showed that the dye adsorption onto ZA is a spontaneous and endothermic. The experimental results indicated that, the adsorption capacity of ZA for removing the cationic dye MG was 98 mg/g, which is being probably dependent on the geometry of the dye molecules.