Possible, but you're unlikely to need much of it. A vegetation capable of feeding a population would also generate enough oxygen to support it. Here's why.
Humans and other animals use oxygen to oxidize organic matter (i.e. food) into CO2 and H2O. On the other hand, plant use CO2 and H2O to synthesize organic matter, and release O2 as a byproduct. So it can be written as
1) CO2 + H2O + light -> food + O2↑
2) food + O2 -> CO2↑ + H2O
No matter what real formula of food is and how you transform it, the O2 parity will hold.
That said, some oxygen may be trapped in metal oxides, like rust. This will have to be replenished. Luckily enough, you'll still need metals (say Al and Fe) to keep the colony going. Those will have to be reduced from oxides, using up a lot of energy and again releasing O2 (or CO2, if you plan using current technology to make iron/steel, but then the plants will capture it) as a byproduct.
Another thing mentioned in the comments is that you'll have to buffer CO2 somewhere, because large CO2 concentrations are bad for humans. The present Earth uses ocean for that, limestone and similar rocks are another great buffer. But you don't have oceans at hand. Of course, you don't want to store CO2 indefinitely, but rather feed it to the plants.