Abstract : We address in this paper the issue of computing global illumination solutions for animation sequences. The princi- pal difﬁculties lie in the computational complexity of global illumination, emphasized by the movement of objects and the large number of frames to compute, as well as the potential for creating temporal discontinuities in the illumination, a particularly dangerous and noticeable artifact. We demonstrate how space-time hierarchical ra- diosity, i.e. the application to the time dimension of a hierarchical decomposition algorithm, can be effectively used to obtain smooth animations: ﬁrst by proposing the integration of spatial clustering in a space-time hierar- chy; second, by changing the wavelet basis used for the temporal dimension. The resulting algorithm is capable of creating time-dependent radiosity solutions efﬁciently.