Increasing zener diode wattage

Can I use 2 zener diodes of the same voltage but .5 watt to make a 1 watt capacity?

If you put them in parallel, no. The tolerance in the breakdown voltage means one will tend to hog the current.

If you put them in series, yes. You could use two zeners in series, each rated at half the total zener voltage you want.

Thanks mate I built a kit that I bought but the 1 watt zener was only .5 watt, I had a spare .5 watt but not a 1 watt so thanks for letting me know cause there is no electronics shops around here and everyone I have asked if two .5 watt zeners together would equal a 1 watt zener have said what is a zener. hehe.
Thanks again.

If you don't mind the zener voltage being about 0.7V you could use a transistor to boost the power.

The zener current will be divided by the transistor's beta.

Just make sure the transistor can safely dissipate 1W: you may need a small heatsink.

Note that this circuit doesn't have the normal 0.6V forward voltage unless you add a rectifier diode in reverse parallel with the transistor.