In this paper, we are reporting on the structural and electronic properties of Gd-Pt surface alloys grown on a Pt(111) substrate. Using scanning tunneling microscopy and spectroscopy combined with density functional theory calculations, we are exploring differences between three different surface alloys, identified as single-layer GdPt2, single-layer GdPt5, and double-layer GdPt5. We show that an appropriate choice of substrate temperature as well as surface coverage with Gd atoms allows for selective growth of all observed surface structures.