<p>How do I build an escape sequence string in hexadecimal notation. </p>

<p>Example:</p>

<pre><code>string s = "\x1A"; // this will create the hex-value 1A or dec-value 26
</code></pre>

<p>I want to be able to build strings with hex-values between 00 to FF like this (in this example 1B)</p>

<pre><code>string s = "\x" + "1B"; // Unrecognized escape sequence
</code></pre>

<p>Maybe there's another way of making hexadecimal strings...</p>

You don't store hexadecimal values in strings.
You can, but it would just be that, a string, and would have to be cast to an integer or a byte to actually read its value.
You can assign a hexadecimal value as a literal to an int or a byte though:
```
```
Byte value = 0x0FF;
int value = 0x1B;
```
```
So, its easily possible to pass an hexadecimal literal into your string:
```
```
string foo = String.Format("{0} hex test", 0x0BB);
```
```
Which would create this string "126 hex test".
But I don't think that's what you wanted?