We study the interplay between coherence and mixedness in meson and neutrino systems. The dynamics of the meson system is treated using the generic decoherence model taking into account the decaying nature of the system. Neutrino dynamics is studied in the context of three flavour oscillations within the framework of a decoherence model recently used in the context of LSND (Liquid Scintillator Neutrino Detector) experiment. For meson systems, the decoherence effect is negligible in the limit of zero CP violation. Interestingly, the average mixedness increases with time for about one lifetime of these particles. For neutrino system, in the context of the model considered, the decoherence effect is maximum for neutrino energy around 30 MeV. Further, the effect of CP violating phase is found to decrease (increase) the coherence in the upper 0 < δ< π (lower π< δ< 2 π) half plane. © 2019, The Author(s).