We fabricate a dispersion-engineered As2S5 microstructured optical fiber for demonstration of frequency conversion in one of the atmospheric-transparent windows in the mid-infrared domain. The experimentally obtained results show that parametric wavelength conversion at 4.5 µm is obtained using fabricated microstructured optical fiber pumped with 200 fs laser pulses of average power of 20 mW at 2 µm. Obtained detuning frequency from the pump frequency was ∼84THz. To the best of our knowledge, the mid-infrared wavelength conversion at 4.5 µm in fiber configuration has been demonstrated for the first time. The experimentally observed result matches well with numerically simulated phase-matching conditions.