Popular catalysts in this group are Ni-based catalysts. A wide variety of Ni-based steam reforming catalysts are commercially available, and they are widely applied in the petrochemical industry. The literature contains numerous studies reporting the use of commercial Ni-based catalysts for tar cracking, which has been shown to be very effective in increasing synthesis gas yield. However, the use of the Ni catalyst in the gasifier is limited due to its fast deactivation caused by coke, chlorine, and alkali metals that may be present in the gasifier (from biomass ash). So far, the use of a nickel catalyst as an additive to the gasifier has had little success.

All these catalysts, when used in-situ, are not promising due to the combination of coking and friability. Using them in secondary beds is more effective. The duration of most-reported catalyst tests has been quite short, especially considering the long activity requirements for expensive catalysts, such as Ni, to be economical. Although downstream gas cleaning methods are reported to be very effective in tar reduction; catalyst deactivation due to impurities in the gas outlet of the gasifier makes catalytic tar cracking economically unfeasible.