Reduction and mitigation of environmental impacts can be achieved through a shift to renewable energy sources, with lignocellulosic biomass emerging as a particularly notable option. The aim of this work is to determine and analyze the composition of agro-industrial residues from rice (husk) and oil palm crops (empty fruit branch, palm kernel shell, and palm mesocarp fiber) originating in Casanare, Colombia and thus understand their potential for utilization in a biorefinery scheme. Fast proximate analysis of each sample of biomass by thermogravimetric analysis was obtained. The performed analyses showed good agreement with the data available in the literature. Moreover, using agricultural information available in public databases, the theoretical annual availability of lignocellulosic biomass generated from these crops was calculated, including hypothetical biorefinery feedstock input estimated to be 735,000 t/year which was also contrasted with other studies concluding that it is enough feedstock for a biorefinery scheme.