We investigated the effect of rapid thermal annealing (RTA) on the sensing and structural characteristics of Ti-doped SnO2 based electrolyte-insulator-semiconductor (EIS) pH sensors. The Ti-doped Tin oxide (SnO2) EIS sensor annealed at 700 °C post deposition annealing, exhibits the best sensing characteristics in terms of sensitivity, linearity, hysteresis and drift rate. This derives from Ti incorporation that improves the thin-film stoichiometry by reducing dangling bonds on the dielectric surface and improves the temperature stability. We further studied the structural, compositional, and morphological characteristics of the deposited thin-film. RTA treatment increases the sensitivity and linearity by creating larger grain size and higher number of surface sites. Sodium (Na+) and potassium (K+) sensing performance was also measured using the fabricated EIS sensors.