The model of the OHO (ODO) quasisymmetric fragment potential energy surface suggested earlier is used for calculation of the H/D substitution effect on the chemical shift (delta(H) or delta(D)) of the bridged nucleus as function of the O-O equilibrium distance R(e)H (2.40 less-than-or-equal-to R(e)H less-than-or-equal-to 2.60 angstrom) for systems with a strong H bond. The theoretical curves are compared with the experimental data. The non-monotonous DELTAdelta(H/D) = delta(H)-delta(D) dependence on R(e)H and on delta(H) as well as the negative and large positive (>0.2 ppm) DELTAdelta(H/D) values are interpreted.