A newly synthesized chitosan stearoyl thiourea derivative is first used for the preconcentration of uranium from sulfate solution prior to its spectrophotometric determination. The effect of optimal adsorption and elution conditions was studied. The equilibrium data were found to be satisfactorily fitting to Langmuir isotherms with a maximum adsorption capacity of 98.75mg/g. Kinetics and thermodynamics studies showed an exothermic pseudo-first-order adsorption process. Interference studies showed a high tolerance of diverse ions. The proposed method was validated and successfully applied for the determination of uranium in certified reference samples and ore samples with satisfactory results.