Silicon-hydrogen bonding configurations, during or after microcrystalline silicon (muc-Si:H) film deposition by catalytic CVD, have been investigated for the first time by real-time in-situ Fourier transform phase modulated infrared ellipsometry (FTPME). FTPME measurements have been performed during and after muc-Si:H film depositions using high, low or variable dilutions of silane in hydrogen. The silicon-hydrogen bonding configurations of muc-Si:H films have been correlated with their corresponding structural properties as deduced from UV-visible ellipsometry analyses. A 4.6% efficiency has been obtained for muc-Si:H n-i-p solar cells, with the i-layer deposited by catalytic CVD at 200 degreesC on a glass substrate using a variable hydrogen dilution process. Further optimization should improve the performance of catalytic CVD muc-Si:H solar cells.