In this research study the economical performance of a solar desiccant cooling system has been assessed. The economical parameters that used to assess the system viability are life cycle analysis and system payback period. The optimisations are carried out for a solar cooling system that has been designed and installed under Central Queensland subtropical climate in Central Queensland University, Rockhampton campus, Australia. The desiccant cooling system consists of a solid desiccant machine, an evaporative cooler and a backup Conventional system. The building cooling load and the system component were modelled using TRNSYS16 under a typical meteorological year of Rockhampton climate TMY. Results showed that by installing 10 m² of solar collectors a 22% of solar fraction will incur and the annual avoided gas emission will be 4.4 tone of Co2. However the payback period will be 22 years if the system resale value was 20% of the total installing cost.