A new method was developed to synthesize uniform anatase TiO2 nanocrystals by the hydrolysis of titanium tetraisopropoxide in nitric acid-isopropyl alcohol aqueous solutions at 353 K. The samples were characterized by XRD, TEM, FE-SEM, and specific surface area determination. In this work, the photocatalytic degradation of 2,4-dinitrophenol in the presence of TiO2 using ultraviolet (UV) light source was investigated in a batch reactor. The effects of various factors, namely TiO2, pH, temperature and concentration, on the degradation performance of 2,4-DNP were studied. The photocatalytic degradation of 2,4-DNP follows the pseudo-first-order kinetics. In acidic or alkaline conditions, the photocatalytic degradation efficiency of 2,4-DNP was greater than that in neutral conditions. Thermodynamic studies have also been carried out and values of standard free energy (deltaG degrees), enthalpy (deltaH degrees) and entropy (deltaS degrees) were calculated.