The thermal denaturation of beta-lactoglobulin solutions (8.5% protein concentration of which 5.8% was beta-lactoglobulin) has been studied by differential scanning calorimetry. For solutions of pH between 1.5 and 8, the denaturation temperature T-d was maximum at pH Delta H-app seemed to be constant from pH 1.5 to 6.6, and 3.5, and the apparent enthalpy change Delta H-app decreased significantly at pH 8.0. With addition of N-ethylmaleimide (NEM) to the beta-lactoglobulin solution (pH 7) in a molar ratio of up to 1:1, the peak temperature T-p increased slightly and then remained constant, for higher molar ratio, while Delta H-app decreased. With addition of dithiolthreithol (DTT), both T-p and Delta H-app decreased drastically. The kinetic parameters of heat denaturation were determined by the Borchardt and Daniels method as a function of pH. At pH 1.5 and 2.5, the denaturation process presented some degree of reversibility which increased with the scan rate of the first heating of the solution. The process could be described as a second-order reaction at pH < pH(i) and at pH 8.0. It seemed to be a first-order reaction at pH 6.0 and 6.6. In the case of irreversibility of the denaturation process, the half-life time was verified by an isothermic method. The heat-induced gelation properties, the gelation time (heat treatment at 80 degrees C) and gelation temperature (heat treatment from 40 to 90 degrees C at 0.1 degrees C min(-1)) were studied with an empirical test and an Instron machine, respectively. The addition of NEM (0-20 mM) and DTT (0-32 mM) gave rise to increasing and reducing gelation time (t(g)) at 80 degrees C, respectively. The onset gelation temperature, determined from the first increase of the apparent Young’s modulus, seemed to be lower than that of the denaturation temperature determined by extrapolation to 0.1 degrees C min(-1) of peak temperatures obtained at various scan rates. It was higher than that of the onset denaturation temperature, determined from the increasing edge of the heat flow measured at 5 degrees C min(-1) (7.5 degrees C for pH 8 solution). The maximum apparent Young’s modulus E(app) observed with increasing heat treatment displayed a higher value at pH 6.6. The experimental results are compared to published data, and they are discussed in terms of electrostatic and hydrophobic interactions and of SH/S-S interchange reactions.