h2o2 a greener alternative to chlorine

you're going to have to post more than that, what application?

Oxidizing potential?

In a general sense I would say yes H2O2 is more environmentally friendly, but it really depends on what reaction is being carried out. This will affect the nature of the reduced oxidant and whether or not it is a polluting by-product.

H2O2 is a relatively poor antibacterial at low concentrations, IIRC. H2O2 injection combined with ozonolysis is much more effective IIRC as it generates free hydroxyl radicals. This however is probably quite a bit pricier than the old standby chlorine (or chloramine treatment)

Again itl depend on what you intend to use it for. While under some conditions H2O2 decomposes to water and oxygen it does not always. And like UC says, a chlorine treatment is probably cheaper

and there are many situations where it cannot be substituted for chlorine