In this paper, a new computerized approach to the determination of low concentrations of 1-ethyl-3-methylimidazolium ethylsulfate ionic liquid (EMISE) and toluene in water is considered. In this approach, an integrated artificial neural network/UV spectroscopy method is designed. The data collected (absorbance data) from the UV spectrometer were transferred into an artificial neural network (ANN) trained computer for estimating the concentrations. Such an integrated ANN/UV spectroscopy system is capable of predicting the EMISE and toluene concentrations in water, based on the created models and patterns, without any previous phenomenological knowledge. The differences between real and estimated EMISE and toluene concentrations are less than 3 and 4%, respectively. The mean difference between the predicted concentrations using the ANN/UV and the real concentration of EMISE and toluene in water is less than 1%.