Abstract The molecular structure of 1,2,4-triazole has been determined by gas phase electron diffraction. The intemuclear distances and bond angles were obtained by applying a least-squares analysis to the experimental intensity. The bond distances ( r g ) and bond angles were N 1 -N 2 = 1.380 ± 0.010 A, N 2 C 3 = 1.329 ± 0.009 A, C 3 -N 4 = 1.348 ± 0.009 A, N 1 -C 5 = 1.377 ± 0.004 A, N 4 C 5 = 1.305 A (calculated value). N-H = 0.990 A, C-H = 1.054 A, ∠N 1 N 2 C 3 = 102.7± 0.5°, ∠N 2 C 3 N 4 = 113.8 ± 1.3°, ∠N 2 N 1 C 5 = 108.9 ± 0.8°, ∠H 1 N 1 N 2 = 110.9°, ∠H 2 C 3 N 4 = 119.2°, ∠H 3 C 5 N 1 = 131.0°, ∠C 3 N 4 C 5 = 105.7° (calculated value) and ∠N 4 C 5 N 1 = 108.7° (calculated value).