N-Dodecane plays a crucial role in surrogate fuels for gasoline and jet fuels. Selecting the right surrogate fuel combination depends on the properties of its individual components. Precise reaction mechanisms are essential to predicting combustion characteristics, including laminar burning velocity and ignition delay times. Unfortunately, data for n-dodecane-air, oxy-n-dodecane with diluents like N2, CO2, H2O, and n-dodecane-H2-air are scarce in the literature. This study aims to bridge this gap. It measured unstretched laminar burning velocity under various conditions using a new cuboidal combustion chamber with optical access and a dedicated heating system. The study used the partial pressure method to prepare combustible mixtures, an electrical spark-ignition system for ignition, and high-speed shadowgraph imaging for flame propagation. A non-linear stretch extrapolation scheme determined unstretched flame speed, and the validation process compared the results with existing data. Finally, simulations using CHEMKIN provided insights into the unstretched laminar burning velocity.