I have a few of these big plastic storage boxes from bigC and i saw some mold appear on objects after being in storage for a couple of months, also books start to smell a bit funky.

Any way how to prevent this happening ?

I would put the box of stuff out in the sun for a few hours before closing it to try to minimise the amount of moisture that would be in there. You see, what's happened is that when you put the stuff in there, you closed the box on humid air which contains moisture and mould spores. By sunning it all, you are reducing the moisture and UV treating the spores on the surfaces. Close the box, then seal it with cling film.

Alternatively, wrap everything in cling film, perhaps.

These are just guesses..what I would do if I had the same problem.

pack with a small amount of rock salt (maybe even simple salt), silica gel or some type of clay absorber ....to absorb the moisture. Not sure if it will work but worth a try

check out this site.

http://www.doityourself.com/stry/3-types-of-moisture-absorbers-explained

good luck

Moth crystals, in the case of stored clothing/bedding etc. Available in supermarkets.