Abstract: I will present our recent theoretical studies on the mechanisms of infra-red (IR) laser induced changes to electron transfer rates in donor–bridge–acceptor species. We explore IR-induced changes to the donor–acceptor coupling, to the validity of the Condon approximation, and to the reaction coordinate distribution. We investigate in general the effects of these IR-induced changes to the electron transfer rates. In a specific guanosine-cytidine hydrogen-bond bridged anthracene/dimethylaniline molecular complex, we find that the dominant IR-induced rate effects arise from changes to the density of states in the Marcus curve crossing region. That is, IR perturbation changes the probability of accessing the activated complex for the ET reactions. IR excitation diminishes the population of the activated complex for forward (activationless) ET, thus slowing the rate. However, IR excitation increases the population of the activated complex for (highly activated) charge recombination ET, thus accelerating the charge recombination rate.