Abstract Nowadays, precise instantaneous real-time application, such as precise navigation, is representing one of the over-increased demands. To provide precise positioning with a few centimeters accuracy for long baselines, the phase ambiguity must be correctly resolved while the receivers are in motion. The research in the field of kinematic real-time ambiguity resolution for long baselines is still one of the inevitable barrier to achieve the ultimate precision of GPS. This research introduces an algorithm for solving the double-difference (DD) Wide-Lane ambiguity of long baselines. The developed algorithm utilizes the wide-laning technique for getting an accurate estimation of the Wide-Lane (WL) ambiguity float solution. The accuracy of this float solution is investigated. A new criterion is used for fixing the correct group of WL ambiguities. A verification of the applied algorithms is done for a kinematic experiment of baseline length ranging from 145 km to 155 km.