I have been using KeePass2 for a while now and I think it is a very good password manager. There also is a portable version and I often read recommendations for KeePass where the portable version is praised as a nifty feature. But is it safe to use any portable password manager on a computer that is not one's own? How easy is it for an adversary to access the passwords on the insecure computer once they are decrypted? Is it safe to use if the PC admin is trustworthy (e.g. at school/work)?
My advice would be to simply never open a password database on a system you do not fully trust. If you must, then put the minimum needed passwords in that 'public' database and make sure you have a solid expiration policy in place.