This study examines two fundamental concerns in the context of organizational change: employees’ perceptions of merger process justice and cognitive trust in the top management team. Our main purpose is to better understand the nature of reciprocal relations between these important constructs through a significant change event. Previous research, building mainly on social exchange theory, has framed trust as a consequence of justice perceptions. More recently, scholars have suggested that this view may be overly simplistic and that trust-related cognitions may also represent an important antecedent of justice perceptions. Using 3-wave longitudinal survey data (N = 622) gathered during a merger process, we tested reciprocal relations over time between cognitive trust in the top management team and perceptions of the merger process justice. In contrast to the conventional unidirectional notion of trust or trust-related cognitions as outcomes of perceived justice, our results show positive reciprocal relations over time between cognitive trust and justice. Our findings also revealed that the positive influence of cognitive trust on subsequent justice perceptions was slightly more robust than the opposite direction. By examining cross-lagged longitudinal relations between these critical psychological reactions, this study contributes across multiple domains of the management literature including trust, justice, and organizational mergers.