The technical advancements made in the modern wireless sensor networks has enabled the realisation of low power modules incorporating various sensors. These developments have pushed the researchers to look at harvesting energy from the ambient environment. The reduced dependence on battery, its recharging or replacement bodes well for the environment. The energy harvesting modules can directly power only a few devices and that too only if they have very low power requirement. The typical energy harvesting module utilises dc-dc converters or rectifier-multiplier modules to achieve appropriate levels of output voltage. This paper provides a review on various power electronic converters used in such energy harvesting applications.