There are 4 things you need to have right.
1. Proper voltage -
most pedals run at 9v, though some need more juice than that. Usually, you can run a normal pedal off of 9.6v too.
2. Proper Current - DC or AC - most are DC
3. Proper barrel polarity - e.g. tip; positve, shaft; negative, or reverse of that
4. Enough amperes - A or mA (for milliamp) - As long as you have more mA than the pedal draws (which usually isn't much), you're fine. When daisy-chaining, you have to add the draw of each pedal.
You should be able to find all this information in the manual (don't have one? Google is your friend).
I've got a couple of these:
http://accessories.musiciansfriend.com/product/Electro-Harmonix-US96DC200BI-9VDC-Guitar-Effects-Power-Supply?sku=150487&rec=product_AThey work for each one of my pedals, and my midi controller (keyboard). It's also the recommendation for the metal muff. I would get one if I were you. $10 is nothing compared to the cost of batteries after a year.