In this article, the effective size of hydrogen in the hydrogen halides forming hydrogen bonded complexes is estimated. The scheme proposed by Bhadane and Gadre [J. Chem. Phys. 107, 5625 (1997)] for estimating the size of hydrogen in HF is extended to the other hydrogen halides (HCl and HBr) and HCN. It is noted that the radius of H atom in HF, HCl, HBr, and HCN are, respectively, 0.55 +/-0.07, 0.74 +/-0.08, 0.80 +/-0.11, and 0.93 +/-0.07 Angstrom. The radii found for HF, HCl, and HBr show a strong inverse correlation with the dipole moment of the HX. From this correlation the radius of H atom in HI is estimated to be 0.90 +/-0.11 Angstrom. By extrapolating to zero dipole moment, the van der Waals radius of H atom is determined to be 1.0 +/-0.1 Angstrom, reasonably close to the value proposed by Pauling, 1.2 Angstrom. (C) 2001 American Institute of Physics.