The adsorption of Mercury (II) and Chromium (III) on orange peel has been studied in batch mode using flame atomic absorption spectroscopy for metal estimation. The effects ofMercury (II) and Chromium(III) ions concentration, agitation time and temperature on adsorption of heavy metals onto orange peel was investigated. The experimental isotherm results were fitted using Langmuir and Freundlich equations. The Langmuir and Freundlichmodel agrees very wellwith experimental data. Themaximumamounts ofMercury (II) and Chromium(III) adsorbed (qm), as evaluated by Freundlich isotherm, were 7.79 mg and 6.43 per gram of powder of orange peel, respectively. All adsorption processes can attain equilibriumwithin 30min and kinetics was well fitted by psesudo-second order equation. It is proposed that the adsorption mechanism was complexation. Thermodynamic parameters (ÄG°, ÄS° and ÄH°) for sorption system was determined at five different temperatures.