Natural zeolite was modified using tandem acid-based treaments in order to create a mesoporous zeolite. Themesoporous zeolite was then characterized using XRD, FTIR, EDX, and AAS. The XRD patterns showed that the structure of zeolite mostly was clinoptilolite. After subjected to the tandem treatment, no significant change in the XRD patterns wasobserved. This indicates that the structure of zeolite is intact. However, the FTIR analysis shows that the wave number of functional groups in the zeolite were shifted after subjected to tandem acid-base treatment, compared to the one of the raw material. However the main functional groups of zeolites still exist after tandem acid-base treatment.The EDX analysis showed that the Si/Al ratio was increased after acid treatments (in average, approximately 1.5 times). In contrast, the Si/Al ratio was decreased from 4.50 to 4.13 after basic treatment. The mesoporous zeolite then was modified further with cobalt (II)-impregnation using incipient wetness method with variation of cobalt loading (2.5; 2.0; 1.5; 1.0; and 0.5 wt%). The Cobalt (II) mesoporous zeolite will then be used as catalyst for the production of FattyAcid Methyl Esters (FAME) from Crude Palm Oil (CPO).