De or het interieurdecoratie?

The correct Dutch article is:

de interieurdecoratie

Rule Words ending in -tie and -sie: almost always de. See the rule

How to use interieurdecoratie

the interieurdecoratiede interieurdecoratie
this interieurdecoratiedeze interieurdecoratie
that interieurdecoratiedie interieurdecoratie
our interieurdecoratieonze interieurdecoratie
your interieurdecoratiejouw interieurdecoratie
every interieurdecoratieelke interieurdecoratie
which interieurdecoratie?welke interieurdecoratie?
a big interieurdecoratie / the big interieurdecoratieeen grote interieurdecoratie, de grote interieurdecoratie