Protocol conversion involves the use of a converter to control communication between two or more protocols such that desired system-level specifications can be satisfied. We investigate this problem in a formal setting and propose, for the first time, a temporal logic based automatic solution to convertibility verification and synthesis. At its core, our technique is based on local module checking and determines the existence of the converter and if a converter exists, it is automatically generated. A number of key features of our technique distinguishes it from all existing formal and/or informal approaches. Firstly, we handle both data and control mismatches using a single unifying module checking based solution. Secondly, the proposed approach uses temporal logic for the specification of correct behaviors (unlike earlier automaton based specifications) which is both elegant and natural to express event ordering and data-matching requirements. Finally, we have experimented extensively with the examples available in existing literature to evaluate the applicability of our technique in a wide range of applications.