Hydrogen peroxide (H₂O₂) was efficiently captured by co-crystallization with enantiomeric and racemic amino acids such as L-phenylalanine, DL-phenylalanine, and DL-asparagine in a dilute aqueous solution of H₂O₂ (30%) to unveil the requisites for efficient capturing of H₂O₂. In further dilute solutions of H₂O₂ (0.5–20%), L-Phe provided certain amounts of co-crystals with H₂O₂; however, co-crystals with H₂O₂ were hardly obtained for DL-Phe and DL-Asn. The efficient H₂O₂ capturing with L-Phe can be ascribed to its layered motif involving water molecules. The results obtained here would contribute to the development of an adsorbent that can efficiently capture H₂O₂ produced in environment-friendly H₂O₂-production systems such as photocatalytic systems.