We report model compound data for primary amide hydrogen exchange in three protected amino acids: N-acetyl-Asn-Nα-methylamide (Asn′), N-acetyl-Gln-Nα-methylamide (Gln′), and N-acetyl-Gly-NH2(Gly′). The solvent exchange rates of the individual E and Z protons have been measured for each of these amino acids in H2O by employing double-resonance NMR techniques. The corresponding acid- and base-catalyzed rate constants (M−1s−1) are kHE= 897, kHz= 806, kOHE= 9.39 × 107, and kOHz= 2.2 × 107for Asn′ at 25 °C; kHE= 1134, kHz= 1095, k0HE= 5.52 × 107, and kOHz= 1.36 × 107for Gln′ at 22 °C; and kHE= 327, kHz= 333, kOHE= 13.48 × 107, and kOHz= 7.87 × 107for Gly′ at 25 °C. Our model compound data provide a basis for evaluating the primary amide hydrogen exchange behavior of these amino acids in peptides and proteins. The acid-catalyzed exchange in these model primary amides appears to take place predominantly through N-protonation. © 1982, American Chemical Society. All rights reserved.