This research aimed at establishing species of active potassium onto 3D-framework of Zeolite NaX that was prepared with a molar ratio of 1Al 2 O 3 :1.65K 2 O:2.2SiO 2 : 5.5 Na 2 O:122H 2 O by hydrothermal synthesis. The potassium acetate/acetic acid buffer solution impregnated catalysts produced the desired K loadings of xKa/NaXs (x values were 9, 10, 11 and 12 wt%). Characterization of catalysts were carried out with FTIR, N2 adsorption-desorption, XRD and CO2-TPD to analyse the respective parameters of the reagents (catalysts) and the product. The 3D-framework of NaX was not destroyed but the surface area and the volume of its micropore were found to have slightly decreased when number of loadings of K was increased. All prepared xKa/NaXs were used to conduct transesterification of Jatropha Curcas Lineaus (JCL) seed oil and methanol at the molar ratio of 1:16. 12K/NaX emerged as the best catalyst which produced 78.39 wt% yield of biodiesel and found to be the highest yield at a reaction time of 3.5 hours. The basicity increased with K loadings and facilitated a better catalytic performance for biodiesel synthesis from this source.