Single crystal X-band EPR spectra of Ti(III) doped C(NH₂)₃M^III(SO₄)₂ ·6H₂O Gu[M^III:Ti]SH, M^III = Ga^III, A1^III) collected at ∼1.9 K, are presented. Principal g values for Gu[Ga:Ti]SH and Gu[A1:Ti]SH of g∥ ∼ 0.965, g⊥ ∼ 0, and g∥ ∼ 0.984, g⊥ ∼ 0, respectively, are derived. The values of g∥are significantly less than that previously reported for Cs[Ga:Ti]SH (g∥∼ 1.161) and this work is principally concerned with accounting for the difference. Analytical expressions are derived for the first-order Jahn-Teller coupling coefficients between the states comprising the ²T_g (T_h) ground term and the twisting librations of the coordinating water molecules, in the framework of the Angular Overlap Model (AOM); and, values of g∥ computed by numerical diagonalisation of the vibronic Hamiltonian. On the basis of differences in the mode of water co-ordination alone, g∥is calculated to increase from 0.965 (Gu[Ga:Ti]SH) to ∼1.10 (Cs[Ga:Ti]SH), in fair agreement with experiment. The EPR spectra of Gu[Ga:Ti]SH contain well-resolved proton superhyperfine structure. The magnitude of the superhyperfine coupling constant far exceeds that inferred from the EPR spectrum of Cs[Ga:Ti]SH, and this too is rationalised in terms of the different stereochemistries of the [Ti(OH₂)₆]³⁺ cation in the two crystal systems.