Amberlite XAD-2 resin impregnated with Cyanex302 has been used to separate and preconcentrate thorium(IV) from associated elements prior to its spectrophotometric determination. The impregnated resin (HL-XAD-2) was characterized by IR spectra. A column packed with HL-XAD-2 was used to understand sorption and desorption behaviour of thorium(IV). The effect of various parameters such as acidity of aqueous phase, nature and concentration of eluting agents, eluent volume and its flow rate were evaluated to optimize conditions for isolation of thorium(IV). Adsorption characteristics of thorium(IV) on HL-XAD-2 in batch studies indicated that the data fit well in Langmuir and Freundlich adsorption isotherm models. The maximum sorption capacity of the modified resin for thorium(IV) was 8.48 mmol g(-1) while the limit of detection (3(TB) was 0.75 mu g dm(-3). A preconcentration factor greater than 100 was achieved. The influence of diverse ions on extraction of thorium(IV) was examined and the method developed was applied for the separation of thorium(IV) from synthetic mixtures and monazite sand. The method is reproducible with a relative standard deviation (R.S.D.) of 0.6%.