To calculate the concentration of HCl in a solution with a pH of 1.5, we can use the formula:

```

[H3O+] = 10^(-pH)

```

where [H3O+] is the concentration of hydrogen ions in moles per liter (M).

In this case, the pH is 1.5, so:

```

[H3O+] = 10^(-1.5) = 0.0316 M

```

Since HCl is a strong acid, it completely dissociates in water, releasing H+ and Cl- ions. Therefore, the concentration of HCl in the solution is also 0.0316 M.