Nowadays for any kind of distributed and multi-level, i.e. complex information systems it is vitally important to represent its data resources in a homogenized form. This paper presents our approach to data synchronization (DS) in complex Process Control Systems (PCS) designed with respect to our real project experience in the domain of PCS for gas-production industry in Ukraine. DS is considered as a stage of more sophisticated approach to data processing called In- telligent Data Engineering (IDE). The IDE framework and some of its modeling aspects are shortly described. The algorithm used at the DS stage for transferring process data between the levels of distributed PCS in XML-format is proposed and implemented. In order to estimate a system performance in a DS publisher node the metrical-based modeling is introduced in our approach.