Condition monitoring is an essential technique which is usually deployed to monitor the health parameters and conditions of a boiler plant in such a way that variations or significant changes can like failure can be identified and proffer adequate solutions to it. It is an important aspect of condition-based maintenance which is used in maintaining an equipment according to its conditions. Thus, this study focused on the fundamental principles of condition monitoring which involve the identification and selection of a physical measurement that will show the deterioration stage and the importance of taking the readings at intervals. More so, the study established that monitoring and measurement should focus more at critical components that have high frequency of failure. Thus, condition-based maintenance of boilers will help in improving the ,availability of the boiler.