The test results of a PCM storage solution for direct steam generation in CSP plants are reported. The high temperature PCM storage was built in 2009 and extensive cycle testing was performed in 2010/2011 in a direct steam test loop, constructed at the power plant Litoral of Endesa in Carboneras, Spain. This storage has a total capacity of 700 kWh and is the first demonstration of a high temperature PCM storage for the two phase heat transfer fluid water/steam in the 100 bar range. Cycling tests have proven very high discharge rates. Operation experience was gained in forced and natural circulation mode and for the first time, operation in once-through mode was demonstrated successfully, showing potential for a significant cost reduction on the peripheral components like steam drum and circulation pump.