Radium sulfate (or radium sulphate) is an inorganic compound with the formula RaSO4 and an average molecular mass of 322.088 g/mol.

[4] It was formerly used in radiotherapy and smoke detectors, but this has been phased out in favor of less hazardous alternatives.

[5] Distance from the radium ion to oxygen is 2.96  Å and the sulfur to oxygen bond length in the sulfate ion is 1.485  Å.

In this compound the ionic radius of the radium ion is 1.66 Å, and it is in ten coordination.

[6] Radium sulfate can form solid solutions with the sulfates of strontium, barium or lead.