Context: Scheduling in the cloud is a complex task due to the number and variety of resources available and the volatility of usage-patterns of resources considering that the resource setting is on the service provider. This is compounded further when security issues and Quality of Service (QoS) are also factored in. Aim: The aim of this research is to address limitations and gaps in current approaches of resource scheduling in cloud computing by developing a Scheduling Security Model (SSM). Method: Considering security as a key element that cloud services rely on which affects the services performance, cost and time concerns within the security constraints of the cloud service. Furthermore, this research will investigate and define the considerable challenges facing trusted and cost-effective resource scheduling in cloud computing environments. The SSM analyses the customer requirements for a service then works to schedule all tasks submitted to run over available resources depending on the security level. It then uses the SSM Algorithm and the Fast-Track technique to reduce the cost and the overall waiting time. Results: The worked examples of the SSM with different scenarios and comparing the SSM against other approaches in the same field show that the SSM can meet the customer requirements for cost effective and the QoS required. Conclusions: The advantages from the results show that the SSM can reduce the overall service cost compared to other approaches.