We used polar-angle x-ray photoelectron diffraction to study the orientation of C2H2, C2H4, and CO on Pt(111) and Pt(110) at 300 K. For C2H2 on Pt(111) and Pt(110) we find no C 1s intensity enhancement, consistent with a side-on bonded species. The same is true for C2H4 on Pt(110), but for C2H2 on Pt(111) we find an enhancement along the surface normal, supporting a vertical ethylidyne species. The C–C bond of C2H2 on Pt(110) remains intact. In the case of saturation coverages of CO, we find a C 1s enhancement along the normal for Pt(111) but not for Pt(110). This supports vertical CO (with the C down) on Pt(111) and tilted CO on Pt(110). Comparison to calculations indirectly supports a model for the tilted phase having p1g1 symmetry. At lower CO coverage on Pt(110) we find vertically adsorbed CO, in line with the idea that the tilting arises from molecular interactions in the adlayer.