2-Amino-1,3,4-triazole (AT), 3-(2-pyridyl)-2-Amino-1,3,4-triazole (2 -AT) and 3-(4-pyridyl)-2-Amino1,3,4-triazole (4 -AT) have been investigated as inhibitors for corrosion of carbon steel in 1 M hydrochloric acid. For this purpose; weight loss, potentiodynamic polarization, AC impedance measurements, current transient techniques were utilized. Polarization curves reveal that three compounds are mixed type inhibitors and inhibition efficiency increases with increasing concentration of compounds. Further, the 4-AT, displayed the best inhibiting characteristics for this system, with a maximum IE of approximately 93% having added only 2 x 10(-3) M. Specimen surfaces were characterized using optical microscope. Calculations of related inhibitors are performed by using HF, MP2 and B3LYP methods with 6-311+G(2d,p) basis sets. (C) 2016 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.