How to add Google Hangout to Pidgin

Before adding account to pidgin. Make sure google singin to less secure apps is allowed.

Or visit this link to enable Less Secure Apps
https://myaccount.google.com/lesssecureapps

If it's done! Add Hangout account #Basic Tab

Protocol: xmpp  
User Name: (your gmail id, without @gmail.com)  
Domain: gmail.com  
Resource: (Keep blank)  
Password: xxxxxxxxx  
Check Remember Password.

#Advanced Tab

Connection Security: Use encryption if available  
Connect Server: talk.google.com

Others leave at it is.

Done...!

Pidgin seems to only support Google Talk - which uses a different protocol. Hangouts employs a proprietary protocol, not compatible with XMPP.

There is a cross-platform client designed specifically for Hangouts (partial support for audio-video), as well as a Python library.