Microscale reactors operate in sub millimeter space dimensions. Their small length scale enables process intensification of mass, heat and momentum transport that influence reaction rates. Hence it's possible to observe the true intrinsic reaction kinetics occurring for a set of reactions. In this work a novel microscale reactor for producing biohydrodeoxygenated diesel is developed and its performance investigated. Biohydrodeoxygenated diesel was produced by removal of oxygen from vegetable oils in presence of hydrogen at high temperatures and pressures on conventional NiMo Al₂O₃ solid hydrotreating catalysts.Reactor was fabricated with photochemical etching to pattern post features on catalyst plates, laser ablation was used to make integrated oil slots and hydrogen hole mixer. Laser welding was used to seal reactor to provide a hematic seal. Six sigma methodologies were used to ensure fabrication method was in control, capable and stable.Sol gel method was used to deposit high surface area alumina on catalyst plate and wet impregnation method used to deposit active NiMo metal catalyst on support. Phosphorus was added to the preparation mixture as a structural promoter. Initial test of reactor with palm olein showed reactor was able to achieve complete conversion to mainly n-alkane liquid products at temperature 325°C, pressure 500psig under 3minutes of liquid residence time. Increase in palm olein concentration showed reaction was limited by stoichiometric hydrogen requirement.Model study of hydrotreating process was done with oleic acid. A 3³ factorial experimental design was done to optimize reaction conditions. Temperature was found to be most important followed by reactor pressure and liquid residence time. Effect of catalyst loading was done at 5wt%, 10wt% and 20wt% to study effect on conversion products. 10wt% loading was found to achieve maximum conversion and hydrodeoxygenation.A detailed mathematical model of reactor system was developed, encompassing flow, mass transport and reaction kinetics. From model developed, mass transport limitation free reaction rate constants was found from a simplex optimization algorithm using Comsol Matlab Live link. Model showed good agreement with experimental data and was used to predict maximum conversion and hydrodeoxygenation conditions.