A simple, sensitive and accurate method was purposed for the micro extraction of molybdenum (IV) as molybdate MoO4- by liquid ion exchange method from 0.5 M HCl media extracted as ion association complex. In this research study all optimum condition and all parameter effect on the extraction efficiency has been studied. The stoichiometric study show the more probable structure of complex extracted was [BG+][HMoO2Cl4], as well as the maximum absorbance wavelength of this complex extracted was 620 nm. Thermodynamic data was H=0.0741 kJ/mol, G=-43.62 kJ/mol, and S =156.64 J/mol K. In addition to some studies about organic solvent effect, electrolyte effect, methanol concentration effect, inferences and application of this method for spectrophotometer determination of Mo (IV) in deferent samples has been carried out
Keywords: Liquid Ion Exchange; Molybdate; Brilliant Green