Question: I've seen some web sites like banking applications that prevent the user from using the back button. If I remember correctly, when you press the back button your session times out.

How can I do this?

Answer: 
**No**, don't do that; don't surprise the user. The back button is there so it can be used. If that's a problem for you, find a way around it, not prevent it.

Use the `Post/Redirect/Get` pattern @benjynito mentioned in the comment.
You cant disable browser's back button just use that, I found [here](https://stackoverflow.com/questions/533867/whats-the-best-method-for-forcing-cache-expiration-in-asp-net)

```
Page.Response.Cache.SetCacheability(HttpCacheability.NoCache);

```