Recently, water contamination by heavy metals is a serious environmental problem, which has been extensively discussed. One of the promising techniques for the separation of heavy metal ions from aqueous solutions is the emulsion liquid membrane (ELM). Liquid membrane technology has been widely used, because of its advantages as a very selective, low cost, and energy saving separation process. In the present study, the applicability of emulsion liquid membrane process for extraction and enrichment of hafnium (IV) from a simulated aqueous solution was investigated. Hafnium is used in control rods for nuclear reactors. It has high resistance to radiation and very high corrosion resistance. Another major application of hafnium is in alloys with other refractory metals, such as tungsten, niobium and tantalum. In this study, the liquid membrane was made up of D2EHPA ( di-2-ethylhexyl phosphoric acid ), Span 80, liquid paraffin, HCl solution and aqueous solution of hafnium as mobile carrier, surfactant, membrane phase, internal phase (stripping agent) and external phase, respectively. The Taguchi method was used to design the experiments. This method is a systematic application of design and analysis of experiments for the purpose of designing and improving product quality without increasing the cost. Taguchi method according to the number of factors and their levels offered an orthogonal array (L 16 ) which is a list of experiments must be performed in a batch extraction system. The –larger-the-better concept was used to get the optimal extraction, and the-smaller-the-better concept was used to get the lowest swelling rate. This method helped us to optimize the extraction and determine the effects of various factors as concentration of carrier, concentration of surfactant, speed of agitation, contact time, and volume ratio of membrane phase to the external phase. The analysis determined the effects of contribution of each of factor on the extraction efficiency and optimum factors to achieve the best extraction efficiency. This analysis showed the speed of agitation with a contribution of 27.133% is the most, and the volume ratio of membrane phase to the external phase with a contribution of 12.479% is the least effective operating factor in the final system response. Also, the extraction efficiency decreased with increasing the carrier, surfactant concentration and speed of agitation. The optimum conditions for hafnium extraction were found as follows: concentration of carrier, concentration of surfactant, speed of agitation, contact time and volume ratio of membrane phase and external phase were 1%v/v, 1.5% v/v, 600 rpm, 10 min, and 0.1, respectively. At these optimum conditions, 10 mL membrane could extract 81.7 % of hafnium from 100 mL aqueous solution, however, the predicted value by the Taguchi method was 86.83%. Solubility of hafnium dioxide (HfO 2 ) was another aim of this work. This colorless solid is one of the most common and stable compounds of hafnium which reacts with strong acids such as sulfuric acid . Results showed hafnium dioxide dissolves in sulfuric acid very slowly and the maximum solubility of this compound of hafnium at 75 o C was 0.467 mol/Lit, i 235 days. No major solubility change was observed after this period. Key words : Hafnium, Extraction, Emulsion liquid membrane, Di-2-ethylhexyl phosphoric acid