What do you mean "i want to read it the browser using .toString function"? Is this Java or C++ or something else? What does your message definition look like?
By default, protocol buffers encodes strings in UTF-8. These characters seem to be encoded correctly as UTF-8, so the "sending" side is doing the right thing, but the code that is reading them is not doing the correct decoding:
à = U+00E0
Escaped in hexadecimal this is: "\xc3\xa0"
Escaped in octal this is: "\303\240"
So you need to decode from UTF-8 to get the correct characters. Hope this helps,
Evan