What is the most secure one way encryption algorithm to encrypt passwords?
MD5 and SHA (1..512) are frequently used, but they are designed for speed what is bad for preventing brute force attacks on encrypted passwords.
The algorithm shouldn’t be too exotic, so that it can be used with common programming languages / runtimes like Java, .NET or Python.
BCrypt or SCrypt. Why? because they where designed to be slow instead of fast.
see also: How to securely hash passwords? on security.stackexchange.com