beta-Casein is a component of casein micelle with amphillic nature and is recognized as a "natively disordered" protein that lacks secondary structures. In this study, the temperature and hydration effects on the dynamics of beta-casein are explored by quasielastic neutron scattering (QENS). An upturn in the mean square displacement (MSD) of hydrated beta-casein indicates an increase of protein flexibility at a temperature of similar to 225 K. Another increase in MSD at similar to 100 K, observed in both dry and hydrated beta-casein, is ascribed to the methyl group rotations, which are not sensitive to hydration. QENS analysis in the energy domain reveals that the fraction of hydrogen atoms participating in motion in a sphere of diffusion is highly hydration dependent and increases with temperature. In the time domain analysis, a logarithmic-like decay is observed in the range of picosecond to nanosecond (beta-relaxation time) in the dynamics of hydrated beta-casein. This dynamical behavior has been observed in hydrated globular and oligomeric proteins. Our temperature-dependent QENS experiments provide evidence that lack of a secondary structure in beta-casein results in higher flexibility in its dynamics and easier reversible thermal unfolding compared to other rigid biomolecules.