Production of sustainable diesel was conducted via hydrogen-free decarboxylation of palm stearin basic soaps. Metal soaps are alkaline earth and transition-metal salts combined with carboxylic acids with 7-22 carbon atoms. Stearin basic soaps were prepared by direct reaction of palm stearin and mixed metal (Ca, Mg, and Zn) hydroxides. The stearin basic soaps were decarboxylated at 370 degrees C for 5 h to produce liquid crude bio-hydrocarbon, also known as sustainable diesel. The stearin basic soaps were characterized by Fourier transform infrared (FTIR) and thermogravimetric analysis, and the resulted liquid bio-hydrocarbons were analyzed by GC equipped with a flame ion detector. The hydroxyl band at 3678 crn(-1) observed from FTIR spectroscopy indicated that the Ca/Mg/Zn ions were associated with the OH ions in the compounds. This proved that the soaps produced from this work were basic metal soaps. The thermal stability of the soaps was examined up to 1000 degrees C, and the decomposition of stearin basic soaps was observed in the range of 300-500 degrees C. The metal contained in the basic soaps affected their thermal characteristics. Liquid crude bio-hydrocarbon with carbon chain length between 8 and 20 has been obtained from decarboxylation of stearin basic soaps. In this study, the decarboxylation of stearin basic soaps resulted in sustainable diesel as the main product. This promising process is expected to open a plethora of opportunities in the production of sustainable diesel.