Little work has been done in the area of engineering thermoplastic biocomposites due to the increased processing temperatures which induce degradation of biomass. Torrefaction has been identified as an effective means of preparing biomass for introduction into engineering thermoplastics such as polyamide 6, however it is an energy and time intensive process. This work looks to microwave induced heating to reduce the required energy costs by 70% over a conventional heating method while producing a more homogeneous higher degree of torrefaction torrefied biomass. The torrefied biomasses were analyzed to understand how time, temperature, and power level affect the yield and thermal stability temperature of the fibers. The effects of the addition of torrefied flax shive, hemp hurd, and sunflower hulls to polyamide 6,6 on mechanical and thermal properties were also studied.