Reduction of tar concentration in biomass gasification with secondary plasma tar cracking unit remains a challenge to meet the requirement for clean syngas energy applications. Typically, the post-treatment of syngas to reduce the tar from an updraft fixed-bed reactor is using secondary plasma tar cracking unit. In this study, an additional trapping train was introduced as a mechanism to harvest byproducts of the tar decomposition process (byproduct carbon functionalized material or BCFM). The measurement in gravimetric and particle size distribution, supported by photoluminescent (PL) and Fourier transform infrared spectroscopy (FT−IR) of BCFM, were conducted to reveal the BCFM characteristic. The gravimetric analysis showed that the application of the secondary plasma tar cracking unit highly reduced the tar concentration. Similarly, the average particle size also decreased significantly. The peak emission spectra of the suspended BCFM particle under the plasma cracking treatment shifted from around 500 nm to around 400 nm. The significant changes in the BCFM functional group occurred due to the successful cracking process. It was concluded that the byproduct received from the plasma cracking process resulted in very low tar content and was revealed to be a carbon functionalized material with a very small size (16.2 nm) and stable suspension.