L-citrulline may be extracted from watermelons using a process which does not require rigorous extraction with alcoholic and/or acidic solvents, or treatment at high temperatures. In the process, the watermelon juice is contacted with an adsorbent effective for adsorption of L-citrulline thereon, and the juice is separated therefrom. The L-citrulline on the adsorbent may then be eluted and recovered. Lycopene-containing microparticles may also be separated from the watermelon juice prior to contact with the adsorbent.