Despite thousands of engineered variants, OPH suffers from a low catalytic efficiency, hindering its action as an OP scavenger. Alterations of the OPH active site residues have enhanced the specificity of native OPH. Here, we focused on testing amino acid substitutions on residues near the enzyme active site to assess how these modulate binding and activity. We computationally investigated single and double mutants to examine the effect of these mutations on the strong interactions occurring in and near the catalytic site. According to the modeling data, additional hydrogen bonds appear in the MD trajectories of the modified OPH enzymes. Hence, changes in the hydrogen bond network surrounding the active site may be important for the function of OPH and must be considered in the design of OPH variants. Strikingly, experimental measurements of kinetics showed that the predicted mutations improved the enzyme activity compared to WT OPH substantially, thus confirming the computational predictions.