The X-ray crystal structure of a racemic mixture of D- and L-penicillamine has been determined. Crystals are monoclinic,P21/c(No. 14), with cell dimensionsa=11.624(3),b=5.919(1),c=11.482(2) Å,β=114.48(2)°, andZ=2, based on the racemate. The structure was determined by standard methods and refined toR1=0.0666,R2=0.0726 for 985 independent reflections. Bond lengths and bond angles do not differ from those in similar structures. Mass spectra and1H and13C NMR spectra are reported ford-penicillamine, and detailed infrared and Raman spectra are reported for solidd-penicillamine hydrochloride,d5-d-penicillamine hydrochloride,d-penicillamine,d4-d-penicillamine, anddl-penicillamine. The Raman spectrum ofd-penicillamine in H2O solution as a function of pH is also report