The α decay of a new isotope 190At has been studied via the 109Ag(84Sr,3n)190At fusion-evaporation reaction by employing a gas-filled recoil separator. An α-particle energy of 7750(20) keV and a half-life of 1.0+1.4−0.4 ms were measured. The measured decay properties correspond to an unhindered α decay, suggesting the same spin and parity of (10−) as those of the final state of the decay. The systematics of the nearby nuclei and the predictions of selected atomic mass models were compared with the measured decay properties.