Arduino Uno R3; digital pins output voltage

Hey all,

So I was trying to use my Arduino with a transistor today; the digital pin wasn't activating the base.
I checked the transistor and the transistor is fine; but I also checked the voltage of the digital pin on the Arduino and it was only .5 volts; The transistor activates at around .7 volts.

My question is; what is the output voltage of the digital pins on the arduino supposed to be.

Thanks.

Did you set the pinMode to OUTPUT?