To secure your chat sessions, look for an OTR -- an "off the record" cryptographic protocol -- chat tool. Options include Gibberbot, IM+ and Xabber. An Android version of open-source Cryptocat was in development last year, but that project has reportedly stalled, unfortunately.
What more can be said about encrypted chat? Not much, except that by using OTR chat tools you can prevent third parties from intercepting your messages. Bonus: you and your chat partners don't have to be using the same OTR tool to encrypt your conversation because the tools are cross compatible.