Reliability Centered Maintenance (RCM) is a maintenance analysis method used to improve a maintenance system that focuses on increasing the reliability of a machine. The condenser is a heat exchange that is used to change the gas fluid phase into a liquid by cooling it. In steam power plant the condenser is used to condense the steam coming out of the steam turbine into air condensate and maintain low pressure conditions on the turbine output side so that the work produced by the turbine is maximized. Because it is very important in the steam power plant cycle, it is important to maintain the reliability of the condenser engine if the condenser reliability decreases it will result in a decrease in production and overall generation efficiency. Therefore, a research is needed to plan maintenance intervals for critical components of the condenser engine so that it can increase engine reliability. The results obtained from this study is an interval schedule design to improve the reliability of the condenser engine and recommendations. The results of the analysis using the RCM method get interval schedule planning, namely at certain time intervals with 80% reliability and proper maintenance recommendations on 3 critical components in the condenser operating unit. Of the 3 components, there are 2 components that are suitable for preventive maintenance and 1 component for corrective maintenance based on the percentage increase in reliability and the rate of damage to each component.