The purpose of this study was oxidative absorption of Hydrogen sulfide by Iron(III) chelated solution.The reactive absorption of hydrogen sulfide into a solution of the ferric chelate of nitrilotriaceticacid (NTA) was studied in this investigation. This work is done by studying the effect of pH, ferric concentration and temperature on Hydrogen sulfide absortion and its conversion percent into sulfur. The experiments have been done in two operational conditions: presence of oxygen and absence of oxygen. The results in presence of oxygen is showed that the optimum pH for experiments is 9.2 that denotes the high solubility of Hydrogen sulfide and bisulfide ion in alkaline solutions. The concentration of ferric ion is depended on Hydrogen sulfide content in sour gas. The rate of input oxygen in system is regulated by proportion of ferric ion to ferrous ion concentration. The iron(III) chelated can be regarded as a pseudocatalyst in the reaction of hydrogen sulfide with oxygen and can be regenerated into the active solution by oxidation of the solution with air or oxygen. The produced sulfur is easily recoverable from the slurry. Another advantage of iron chelate based processes is that they essentially operate at ambient conditions and are selective to hydrogen sulfide relative to carbon dioxide. A computer simulation also is done to study the effect of change pH and ferric ion concentration of solution with time.