The Triassic Muschelkalk carbonates are a unique play in NW Europe, producing hydrocarbons onshore The Netherlands. This paper aims at a comprehensive description of these relatively unknown reservoirs and speculates on additional play potential outside of the current production areas. The Muschelkalk Formation consists of partially porous Lower and Upper Muschelkalk carbonates separated by tight Middle Muschelkalk evaporites. The 100 m thick Lower Muschelkalk holds 1.9 BCM gas in the De Wijk Field. The reservoir is a limestone–dolomite–marl succession producing from several decimetres thick calcisilitic dolo-mudstones encased in tight lime-mudstones. The reservoir shows a stratified architecture composed of 16 cycles with thin but laterally continuous porous units. Good reservoir quality facies are concentrated in the upper third of these cycles. Porosities vary from 6 to 27%, (average 12%) and permeabilities range from 0.01 to 32 mD (average 0.06 mD). The reservoir rocks represent inner ramp sediments of a ...