Hydrogen bonds formed in ladder polyphenylsilsesquioxane (Ph-LPSQ)/polyisophthalamide (C-n-PA) composites and their electrospun fibers were studied by ATR FT-IR in detail. It has been found that the peak position of hydrogen bonded N-H stretching vibration in the electrospun composite fibers shifts to higher wavenumber compared to that produced in the composite powders. Moreover, the wavenumber shift increases with increasing electrospinning voltage. This is caused by the transformation of N-H center dot center dot center dot O=C hydrogen bonds into N-H center dot center dot center dot OSi2 ones during the electrospinning process. Possible structure models for the composite powders and the electrospun composite fibers were proposed.