Vinegar is a mild acid which can kill 82% of mold species. However it also has the advantages of being natural and safe. Vinegar is non-toxic and doesn't give off dangerous fumes like bleach does.
How to Kill Mold with Vinegar
To kill mold with vinegar, use white distilled vinegar which you can buy cheaply from the supermarket.
Pour some vinegar into a spray bottle without watering it down.
Spray the vinegar onto the moldy surface and leave it to sit for an hour.
Wipe clean the area with water and allow the surface to dry. Any smell from the vinegar should clear within a few hours.
If you want to use vinegar to prevent mold growing on surfaces just spray vinegar on the surface and leave it. Repeat this every few days to ensure the surface will stay mold-free. You can even mop your tiled bathroom floor or other hard non-porous floors with vinegar if you are worried about mold growing on them.