Background: The 1-minute sit-to-stand test (STS) is a simple exercise capacity test, but has not yet been thoroughly validated in COPD. Aims: We aimed to assess the measurement properties and physiological response to the STS. Methods: Patients with COPD who took part in an inpatient pulmonary rehabilitation (PR) programme were included from 2 studies (Switzerland (CH): n=52 and Germany (D): n=205). We assessed the STS, 6MWT and patient reported outcomes pre and post PR. 18 patients conducted additional STSs with cardiopulmonary gas-analysis. We calculated intraclass correlation coefficients (ICCs) between two STSs at baseline (learning effect) and follow-up (reliability) (CH), Pearson correlation coefficients (PCCs) of the STS with previously validated measures (validity), standardised response means (SRM) (responsiveness) and the minimal important difference (MID) with anchor and distributional methods. Results: The mean STS scores at baseline were 16.5±6.6 (CH) and 24.2±7.5 (D). The change scores were 3.6±4.1 (CH) and 4.0±4.3 (D). The ICCs were 0.93 (95%CI: 0.83-0.97) for learning effect and 0.99 (0.97-1.00) for reliability. The PCCs between the STS and 6MWT were 0.59 (CH) and 0.64 (D). The SRMs were 1.16 (0.86-1.45) (CH) and 0.92 (0.78-1.07) (D). The MID was estimated as 3 repetitions. Figure 1 shows the gas exchange response to the STS. Conclusion: The STS is reliable, valid and responsive for measuring exercise capacity in COPD.