When a visual stimulus is quickly followed in time by a second visual stimulus, we are normally unable to perceive it consciously. This study examined how affective states influence this temporal limit of conscious perception. Using a masked visual perception task, we found that the temporal threshold for access to consciousness is decreased in negative mood and increased in positive mood. To identify the brain mechanisms associated with this effect, we analysed brain oscillations. The mood-induced differences in perception performance were associated with differences in ongoing alpha power (around 10 Hz) before stimulus presentation. Additionally, after stimulus presentation, the better performance during negative mood was associated with enhanced global coordination of neuronal activity of theta oscillations (around 5 Hz). Thus, the effect of mood on the speed of conscious perception seems to depend on changes in oscillatory brain activity, rendering the cognitive system more or less sensitive to incoming stimuli.