The dynamic mechanical behavior of a compound styrene-butadiene rubber (SBR-1502) was measured in the frequency range from 10(-3) to 10 Hz and between 80 and 300 K. The loss tangent data reveal two transitions, alpha and beta, characterized by the temperatures T-alpha and T-beta. Both processes showed an Arrhenius behavior and so the activation energies were calculated. A molecular interpretation on the beta relaxation in SBR is also introduced.