Crystalline phase pure ZSM-22 framework (bulk molar ratio 45) has been synthesized and employed to investigate the effect of tailored Bransted acidity on hydroisomerization of n-hexadecane. Typically, ZSM-22 framework Bronsted acidity is tailored with Group-II cations viz. Mg2+, Ba2+ and Ca2+, by means of ion-exchange method. The physico-chemical characterization of the various samples have been performed using powder X-ray diffraction, nitrogen adsorption-desorption isotherm measurement at 77K, inductively coupled plasma (ICP) and scanning electron microscopy (SEM) techniques. The framework acidity w.r.t. Bronsted level has been characterized and estimated using ammonia temperature programmed desorption (NH3-TPD) and Fourier transform infrared spectroscopy of Pyridine (Py-FTIR) as a function of temperature, respectively. Hydroisomerization of n-hexadecane is performed over Pt (0.45 wt%)/M-H-ZSM-22 samples (in extrudate form) in an up-flow fixed bed reactor and the effect of process parameters namely temperature and WHSV have been investigated. Based on the obtained results, Pt/Ca-H-ZSM-22 framework with calcium exchange level of about 10% showed the optimum performance among all the prepared samples with maximum isomer selectivity, yield (85.8 and 77.8%, respectively) Pt/H-ZSM-22 sample (79.3 and 70.5%, respectively) and more importantly branching index of 4 in favor of mono-branched isomers, at a conversion level of about 90% at 585 K. Among Group II cations, calcium exchange over ZSM-22 framework is found to be effective in enhancing selectivity in favor of mono-branched isomers. In view of this, the role of tailored acidity through Group II cation exchange for optimization of degree of branching during hydroisomerization of long chain n-paraffin is discussed. Furthermore, the relative maximization of mono-branched isomers using calcium exchange is expected to offer platform for development of hydroisomerization catalyst with minimum cetane loss. (C) 2015 Elsevier B.V. All rights reserved.