Password Storage Best Practice

[eluser]Ziggomat1k[/eluser]
I'm currently writing an app in Codeigniter that accesses several data export APIs. In order to do this, I have to have the client's credentials available to me. Originally, I had planned on hashing their credentials but have since realized that hashing them makes them irretrievable.

Currently, the user names and passwords are just stored in the DB. What would be best practice for making these credentials dynamically available while still keeping them secure?