Liquid air energy storage (LAES) is a novel technology for grid scale electrical energy storage in the form of liquid air. At commercial scale LAES rated output power is expected in the range 10 to 100 MWe, while the storage capacity of the order of 100s of MWhe. LAES comprises three processes: charging, consisting in air liquefaction; storage, involving preservation of air in liquid form; and discharge, consisting in evaporation and expansion of liquid air to produce electricity. Compared to pumped-hydro and compressed air energy storage, LAES has no orographic constrains and employs “off-shelf” components commercially available. In this paper we present the results gathered during the operation of the first LAES pilot plant currently installed at the University of Birmingham (UK). The pilot plant has a rated power of 350 kWe and an energy capacity of 2.5 MWh. It comprises key components including an hot thermal energy storage, used to recover waste heat, and an high grade cold thermal store to recycle cold thermal energy. We show both charging/discharging dynamics and illustrate the lessons learn from field operation of the pilot plant.