We studied the immediate effects of transient non-invasive transcutaneous vagal nerve stimulation (tVNS) on heathy naïve human participants using high density EEG and pupilometery. We found that tVNS induce transient pupil dilation as in in animal models, and attenuates EEG alpha oscillations anti correlated with arousal. Our results support the use of tVNS as non-invasive neuormodulation tool for neuroscientific research and for developing novel clinical applications.