$$pH = -\log[\text{H}_3\text{O}^+]$$

where [H3O+] represents the hydronium ion concentration in moles per liter (M).

Given the hydronium ion concentration [H3O+] = 5.03 × 10-10 M, we can calculate the pH as follows:

$$pH = - \log (5.03 \times 10^{-10})$$

$$pH = 9.30$$

Therefore, the pH of the solution is 9.30.