Potential Evapotranspiration (PET) functions as an indicator to estimate the amount of water loss to atmosphere. Over the years, global climate change eventually led to the change of PET capacity and this had affected the agricultural sector and water resource management. The objective of this study was to determine the best PET estimation method as well as to carry out the trend analysis and stationarity test of PET in Peninsular Malaysia. The Mann-Kendall (MK) test and Sen's Slope estimator were applied for the trend analysis while the Augmented Dickey-Fuller (ADF) test and Kwiatkowski–Phillips–Schmidt–Shin (KPSS) test were applied for the stationarity test. The findings showed that Pulau Langkawi and Kuantan stations exhibited increasing trend while Bayan Lepas station exhibited decreasing trend for the daily, monthly, and annual PET time series. The daily, monthly, and annual PET time series at Bayan Lepas, Ipoh, Subang and Muadzam Shah stations were found to be stationary. Overall, the PET trend was found to be higher at the coastal regions and stationary at the mountainous region.