This experiment was arranged to investigate the ability of hydrotime model (θH) for estimating soybean seed germination (cv. ‘JK’) under different accelerated aging periods (AAP, 0, 24, 48, and 72 h) at each of the following water potentials (ψ, 0, − 0.12, − 0.24, and − 0.36 MPa). Results indicated that both germination percentage (GP) and germination rate (GR) significantly influenced by ψ, AAP, and their interactions (P < 0.01). GP and GR decreased by 62.6 and 47.3% with longer AAP from 0 to 72 h and by 90.7 and 81.5% with lower ψ from zero to − 0.36 MPa as compared to the control, respectively. Therefore, the effect of ψ on GP and GR was more than AAP. The θH value was constant (~ 6.71 MPa h−1) till 50.6 h AAP and then linearly declined with the rate of 0.1545 MPa h−1 per hour increase in AAP until 72 h (~ 50% lower than its initial value). The ψb(50) value was − 0.343 MPa in the control and then increased (became more positive) by ~ 70% until 72 h AAP (− 0.104 MPa). In general, GP and GR of soybean declined with the increasing ψb(50) which can be due to cell membrane damage and reduce the activity of enzymes and organelles during AAP. Based on our findings, the θH model could describe well these relationships and their parameters can nicely be used for simulating soybean seed germination under this condition.