HAYNES 188 (HN-188)* is a commonly used Co-Ni-Cr-W superalloy since 1960s (*HAYNES is a registered trademark of Haynes International, Kokomo, IN, USA). Because of its excellent high temperature strength, good resistance to hot corrosion, and wear resistance, HN-188 has found extensive applications such as afterburner components and combustors. Even the alloy has been investigated previously, new industrial processes such as laser beam applications i.e., laser beam welding, and laser powder deposition, increase the demand on theoretical and experimental knowledge. In this research, laser beam welding characteristics of HN-188 superalloy (2.1 mm thick) were investigated. Two different heat inputs (61.3 J/mm and 90.1 J/mm) and travel speeds (46.5 mm/s and 22.2 mm/s) were applied. The base metal (BM), fusion zone (FZ), heat affected zone (HAZ) and the geometry of weld seams were characterized using optical microscopy (OM) and scanning electron microscopy (SEM).