How can i obtain eu passport?

31 yo australian no relatives or ancestry from europe. have been offered job in europe but require eu passport any help appreciated

You will have to qualify for citizenship under the laws of any one of the EU countries - they each have their own immigration and naturalization processes, some easier than others. Look up each one and see what their laws say.

contact the passport agency
go to the post office they can tell you exactly where you need to go
You have to become a citizen of one of the EU countries to get an EU passport. If you want to work in an EU country it should be enough for you to get a working permit (you shouldn't need a passport, unless the nature of the job requires it) and getting a working permit should be pretty easy if you've already been offered a job.

Try contacting the Immigration Office or Ministry of Foreign Affairs in the country you have in mind and ask them for detailed information.
You don't need an EU passport to work in EU. You are going to a particular EU country, so reaserch their laws.