Based on comprehensive conformational analysis at the DFT B3LYP/6-31G(d,p) level of theory [Ye.P. Yurenko et al., J. Phys. Chem. B, 111 (2007) 9655] 13 types of intramolecular hydrogen bonds (171 in total number, from I to 3 H-bonds per conformer) were identified in the 92 allowed conformers of isolated thymidine, a DNA canonical nucleoside. Weak interactions CH...O, OH...HC and CH...HC were analyzed by all the Koch and Popelier criteria of H-bonding. Quite satisfactory linear correlation was found between Grabowski complex measure of H-bond strength Delta(com) and logansen H-bond energy -Delta H for 17 OH...O hydrogen bonds. (C) 2007 Elsevier B.V. All rights reserved.