Different effects for phosphoric acid and calcium citrate on properties of magnesium oxysulfate cement

•The effects of two chemical additives on the performance of MOSC was compared.•The mechanism of the different effects of two chemical additives on the properties of MOSc was analyzed.•The decrease of hydration rate of MOSc is beneficial to the crystallization development of 5·1·7 phase.•The 5·1·7 phase with low crystallinity or 5·1·n phase may be another factor for the reduction of compressive strength of MOSc after immersion.