In this paper the magnetic and magneto-optical properties as well as the recording performance of Co/Pt layered structures are described. Two different structures are investigated: One with 4 Å Co and 9 Å Pt layers and the other with 4 Å Co and 18 Å thick Pt layers. We show with Lorentz microscopy that very regular domains can be written in these layers and we relate these results to the measured recording performance. Domain patterns are written in two different ways, with laser modulation (LM) and magnetic field modulation (MFM). With LM very regularly shaped domains are formed. With MFM we find a strong tendency for subdomain formation.