The adsorption of enantiomers and a racemic mixture of tyrosine (tyr) on Cu(111) has been investigatedby cyclic voltammetry and electrochemical scanning tunneling microscopy. d-tyr and l-tyr molecules adsorbon Cu(111) and show a (4 × 4) structure. The mirror symmetry between two adlayers is demonstrated byhigh-resolution scanning tunneling microscope images. The spontaneous separation of racemate intohomochiral domains is observed. The result presented here is hoped to supply direct evidence for the chiraladlayer ordering at the solid/liquid interface.