Time-resolved small-angle light scattering was used to study phase separation phenomena of the water–octane–tetraethylene glycol monodecyl ether (C10E4) microemulsion system. More precisely, a surfactant volume fraction φs at which the system separates into two different bicontinuous phases was used. Under these conditions, the contributions to the structure factors of both the macrophase and the microphase separation domains that occur simultaneously could be observed. Time evolution of the characteristic wave vectors and of the intensity distributions are discussed in the framework of dynamical scaling theories and compared with the results of molecular dynamics simulations. A comparison of the data obtained with the numerical analysis gives a clear indication that in this complex bicontinuous system, the phase-separation process occurs differently than in simple critical mixtures. It was also observed that the kinetics of the phase separation depend strongly on the competition between macro and micro separating domains.