Time processing requires the estimation of events' duration per se, but also seems to trigger attentional and memory processes. To isolate attentional processes, we investigated neural correlates of anticipatory attention when estimating stimulus duration. Magneto-encephalographic (MEG) activity was recorded in fourteen healthy right-handed volunteers, who were cued to attend to either the duration or the intensity of a visual stimulus. We report an increase of gamma-band oscillations over right fronto-central and parietal regions when subjects are prompted to attend to duration, which is not present when subjects are cued to attend to intensity. Cue-related alpha power decreases over occipito-parietal regions were similar in the two conditions. Our results support the hypothesis that the right fronto-parietal network observed repeatedly in time estimation imaging studies is indeed involved in attentional control rather than stimulus processing. Moreover, they underline the supramodal property of time dimension that goes beyond purely perceptive features.