While private clouds provide high security and low cost for scheduling workflow, public clouds in addition to higher costs, are potentially exposed to the risk of data and computation breach. However, in real world, needs for high performance resources and high capacity storage devices encourage organizations to use resources in public clouds. Task scheduling, therefore, is one of the most important challenges in cloud computing. In this paper, whilst considering the security issue, a new scheduling method is proposed for workflow applications in hybrid cloud. Specifically, sensitivity of tasks, which has been considered in recent works, as well as security requirement for data and security strength for both resources and channels are taken into account. The proposed scheduling method is implemented in improved Particle Swarm Optimization (PSO-WSCS) algorithm. The goal function, is minimizing the security distance of data and workflow from security strengths of resources and channels such that time and budget constraints are observed. The proposed PSO-WSCS algorithm, which is based on original PSO with some modifications, is compared with three similar scheduling algorithms, namely VNPSO, MPSO and MPSO-SA, in hybrid cloud. Evaluations show the effectiveness of our algorithm in finding resources whose security aspects have high resemblance to the security requirements. This is displayed by an average improvement of 40% in the studied samples.