Abstract: Background and Objective: Cognitive radio has been proposed to overcome the problem of spectrum scarcity that arises due to fixed allocation of the channel. One of the greatest challenges of this technology is how the unlicensed users can share the licensed spectrum based on required quality of service. In most cases, secondary users may require handoff when licensed users claim back their channels. The objective of this study was to reduce the dropping probability of high priority secondary users during handoff. Materials and Methods: To overcome the challenge of handoff when licensed users claim back their channels, a post-reserved channel sharing scheme with imperfect sensing was proposed. In this scheme, high priority and low priority secondary users (SUs) are assigned to general idle sub-channels in a FCFS order. If the general idle sub-channels are full, high priority SUs are assigned to the reserved sub-channels, while the low priority SUs are dropped. The proposed post-reserved channel sharing scheme is modeled using the continuous Markov chain. Results: The numerical results obtained from the derived models show that high priority handoff calls perform better under the post-reserved channel allocation scheme than under the pre-reserved scheme in terms of reduced dropping probability. On the other hand, low priority secondary user’s calls perform better under the pre-reserved scheme compared to the post-reserved scheme. Conclusion: It can be concluded that high priority handoff calls perform better under the post-reserved channel scheme than under the pre-reserved channel allocation scheme.