The alkylation of biomass-derived aromatic oxygenates (anisole, phenol, guaiacol, and m-cresol) with furfural alcohol and 5-hydroxymethylfurfural is a step toward high-density biofuel. Conversion and selectivity trends toward monoalkylated products were evaluated in the presence of different operational conditions in batch process. It was observed that FeCl3 was the best catalytic system for phenol alkylation and produced 84.7% monoalkylated product at 80 degrees C, for 30 min in a continuous nitrogen flow. Guaiacol, anisole, and m-cresol gave 100%, 79.6%, and 85.5% monoalkylated product, respectively. The effect of nitrogen pressure on alkylation was reported for the first time; the monoalkylated product selectivity of phenol, anisole, m-cresol reached 95.5%, 88.7%, and 100% at 4, 8, and 10 bar of N-2 pressure, respectively. The alkylation of 5-hydroxymethylfurfural (5-HMF) with aromatic oxygenates was also studied by replacing furfuryl alcohol with 5-HMF. The selectivity of the monoalkylated product reached almost 100% with every oxygenate, but alkylation of 5-HMF was slower compared to furfuryl alcohol and longer time was required.