Hi Oliver, are you also possibly using an old version of Blender or something?

Over here doing a quick test with the default OBJ importer in Blender 2.49 seems to preserve materials fine for me.

Just make sure in MoI under Options > Import/Export > OBJ options, you have both "Write material assignments" and "Write .mtl file" enabled.

This in MoI:



Just using the default Blender OBJ import options which is like this:



Gives me this result in Blender:



- Michael