Atomic steps and atomic structures in the reconstruction of Pt and Ir surfaces, induced by nanosecond pulsed-laser heating, have been studied in field ion microscopy. Pt and Ir (110) planes reconstruct from the (1×1) to the (1×2) by breaking of the [110] atom rows into fragments of two to several atoms and by lateral and cross-channel jumps of these fragments. Jumps of single atoms are rare. The (1×2) structure we have observed is consistent with the ‘‘simple’’ missing row model. The hexagonal structure of the Ir(001) (1×5) reconstructed surface has been directly observed for the first time. The image structure appears to be consistent with the models proposed from low-energy electron diffraction studies although the detail buckling may depend on the size of the plane.