Cowpea (Vigna unguiculata) is a bean widely consumed worldwide. Its slow and discontinuous hydration make its improvement desirable toward industrialization. This work evaluated the influence of pH of the soaking solutions on the rehydration behaviour of Cowpea. The hydration process was conducted at 25 oC under immersion in four different soaking solutions at the pH levels of 3, 6 (natural value), 9 and 12, prepared using HCl or NaOH. A downward concave shape behaviour was observed for the moisture content against soaking time profile which was described using both Peleg and Miano et al. models. Although both models described the data well, the Miano et al. model fitted better, owing to its higher number of parameters (4) compared to Peleg model with only 2. The pH value of soaking solution, pH 12 was constant all through the entire process, while the values of other pH solutions converged toward 6.0 (natural value). This could be attributed to the ionization and dissociation of cellular components in the grains, as well as its leakage. The equilibrium moisture content was reduced by 9% for solution with pH 12 in relation to the natural pH (6); while for other solutions with pH 3-9, it relatively the same (150 % db). The hydration rate at pH 12 increased by approximately 240% in relation to pH 6. For the other solutions, the values were also relatively the same (2.77 s-1). The processing time to reach the equilibrium moisture point for pH 12 was 240 minutes, and ~330 minutes for others. Conclusively, the pH of hydrating solution has significant influence on the hydration of Cowpea. The contribution of this work is toward grain hydration behaviour description and possible optimized enhancement.