Aims: The aim of this study is to assess the availability of steam and gas turbine units of a thermal power station using Markovian Approach. Place and Duration of Study: Operational data from 2003 to 2012 were collected from a thermal power station in Nigeria. These raw data represents records of plant generation capabilities as well as other inherent daily conditions that will enhance the success of this study. Methodology: Relevant indices such as Repair Rate (μ), Failure Rate (λ), Mean Time to Repair (MTTR), Mean Time to Failure (MTTF) and Mean Time Between Failures (MTBF) was determined for each of these states. For each state, state probability are also calculated through repair rate and failure rate of the corresponding state.