polyurethane(PU) polymer, due to its biocompatiability, weather resistance, and favorable physical properties, finds a number of applications in medical implants, protective coatings, and as a prototype material for structural components in MEMS devices. An excimer laser (wavelength =248 nm, FWHM =25 ns) is employed for micromachining of polyurethane (PU) polymer. For air environment, the ablation rate is 0.18 mu m/ pulse and for underwater environment, the ablation rate is 0.07 mu m/pulse (with underwater ablation threshold as 0.10J/cm(2)), which concluded low taper angles (similar to 32 degrees) for in air as compared to high taper angles (similar to 65 degrees) with underwater micromachining. The experimental results for air and under water micromachining demonstrate ablation process as a combination of photo-thermal and photo-chemical mechanism. (C) 2014 Elsevier B.V. All rights reserved.