Abstract: Maintaining a physiological seed quality in storage period is necessary. Deterioration of rubber seeds during storage period is a decrease of physiological quality that causes physiological changes in seed that reduce seed viability. Rubber seed has a relatively high water content, respiration and metabolism and remained active during storage period. The PEG 6000 has an osmotic potential, that can be used in seed storage period to limit changes in water content and oxygen in the storage medium that can induce secondary dormancy. The purpose of this research was to examine the physiological change of rubber seed after stored with PEG 6000 for 16 days to induce secondary dormancy in maintaining seed viability. This study examined differences in treatment with and without PEG 6000 30% with 4 replications using t-test at α = 5%. Parameters observed were fungal seed found in storage (%), seed germination (%), moisture content (%), water activity (aw), O2 consumption (mL kg–1 jam), CO2 production (mL kg–1 jam), total sugar content (%), protein content (%), ash content (%), fat content (%), electrical conductivity (μmhos cm–2 g–1), peroxide value (%), seed hardness (kgf) and germination of seeds after storage period (%). The results showed that the physiology of shelled rubber during storage for 16 days with the PEG 6000 30% coating would be changed not significantly with a viability of 99%.