Abstract: Carbon fiber reinforced gelatin (C/Gel) biocomposites were prepared by solution and vapor cross-linked modes, respectively. The swelling behavior of the solution cross-linked C_L/Gel and C_S/Gel composites did not follow the Fick's law; instead, it could be described by a second-order rate equation. Neither the Fick's law nor the second-order rate equation could be used to describe the swelling kinetics of the vapor cross-linked C_L/Gel composite that exhibited a lower swelling ratio in comparison to the solution cross-linked counterpart. The maximum swelling ratio (W_∞) and swelling rate (K_∞) for the solution cross-linked C_L/Gel and C_S/Gel composites were improved with the increase of fiber volume fraction, the latter showing lower W_∞ and K_∞ values at an identical fiber level. It is concluded that the fiber architecture and fiber content had an obvious effect on the swelling behavior of the C/Gel composites. The mechanisms governing the phenomena have been discussed in the present paper.