By achieving simulation of hydrodynamics in a bubble column reactor,have taken an important step towards designing an efficient slurry reactor for large-scale conversion of synthesis gas to liquid hydrocarbons. The simulation allows determining gas holdup, a key variable affecting the reaction rate of gasto-liquid (GTL) conversion using Fischer-Tropsch (FT) chemistry.This information is important because there is the potential for the wide application of FT for conversion of refinery residues,an ever-increasing problem on a worldwide basis. A slurry reactor offers one such method,but detailed knowledge of the hydrodynamics of commercial-size reactors is required.Validated two-dimensional computational fluid dynamicó modeling allows simulating a commercial reactor.This work have two parts, the first part experimental work with bubble column with specific conditions and the second deals with computational fluid dynamics CFD for bubble column have the same geometry and operating conditions.The experiments of bubble column of (0.081m diameter and 1.03m height) were carried out with air-water, CO-water, and Air-NaCl six concentrations of NaCl solutions from 0.24 M to 0.8 M.2 This study is to clarify experimentally the effect of superficial gas velocity on the gas holdup, and the mass transfer coefficient (kLa) where each of them increases as the superficial gas velocity increase. NaCl addition will increase the transition velocity, and the gas holdup for certain concentration and superficial gas velocity Three-D simulation was applied in this work. Gas holdup computational results using Ansys CFX used on Eulerian-Eulerian multiphase model have been compared to experimental data. These results for air-water system were encouraging.