In article, we have reported the thermodynamic Van’t Hoff equation in study of dissociation process of solute benzoic acid into water solvent at ordinary temperature in between of 288 K to 318 K. At this temperature range, the value of dissociation constant (Kc) of that acid is being to found as -4.169, -4.045, -3.993, -3.885, -3.848 and -3.788, for given concentrations of NaCl (sodium chloride) volume as its six ionic strength of 0.00, 0.05, 0.10, 0.30, 0.40 and 0.50 M, respectively, which are titrimetrically analyzed with 0.05 M basic NaOH (sodium hydroxide) solution. The pH value of each solution is measured by using of digital pH-meter as well. Here, observation reported that the pH value of benzoic acid into water at that range of temperature is being inversely related to concentrations of NaCl. In graph, a value of benzoic acid with there ionic strength (I) is plotted versus equilibrium dissociation constant (Kc) at specific 298 K, have shown the dissociation of acid into water is increases as increase the ionic strength. But, comparatively, the graph for increasing temperature range to thermodynamic dissociation constant (Ka) have shown that the dissociation is not always increases as if increases temperature.