Provided are a process and an apparatus for the purification of nitric oxide for industrial, analytical, and research purposes. Nitric Oxide (chemical formula NO) is also referred as nitrogen monoxide. It is a colorless gas having extremely high reactivity toward oxygen and other oxidants present in the atmosphere. The method to purify Nitric Oxide consists in passing a steady flow of a mixture of impure Nitric Oxide, optionally diluted in an inert gas, through a filter composed of hydroxides of alkali and earth alkali metal kept at a temperature below 298 K. The Nitric Oxide is then passed through a second filter and finally collected in a sealed container. The second step has the function to remove those impurities that may not have been removed in the first step.