Introduction: The ability to monitor ventilatory responses during activities of daily living (ADLs) in adults with COPD has obvious clinical implications. Objectives: To test the validity of the Hexoskin biometric vest (HEXO) to measure ventilation (VE), tidal volume (VT), breathing frequency (Bf), inspiratory capacity (IC) and inspiratory reserve volume (IRV) compared with a pneumotachograph (Ptach) at rest and during exercise in COPD. Methods: Ventilatory parameters were collected using the HEXO and Ptach in 16 men with COPD (FEV1=51±19% predicted) under 4 conditions: at rest while supine (5-min), sitting (5-min) and standing (3-min); and during 3-min of stair stepping exercise at 16 steps/min. Results: Analysis of each patient’s mean values recorded using HEXO and Ptach under each of the 4 conditions revealed moderate-to-fair coefficients of variation (CV) and low-to-high intraclass correlation coefficients (ICC) for VE (CV, 8.3-32.8%; ICC, 0.23-0.76), VT (CV, 6.0-25.0%; ICC, 0.20-0.92), Bf (CV, 4.3-9.3%; ICC, 0.66-0.95), IC (CV, 12.0-18.8%; ICC, 0.12-0.68) and IRV (CV, 19.1-30.5%; ICC, 0.03-0.68). Bland-Altman results indicated low bias (B) and low-to-moderate 95% limits of agreement (LA) for VE (B, 1.1±5.4 L/min; LA, -9.6 to +11.7 L/min), VT (B, -0.01±0.25 L; LA, -0.48 to +0.51 L), Bf (B, -0.5±1.9 bpm; LA, -4.3 to +3.2 bpm), IC (B, -0.3±0.6 L; LA, -1.4 to +0.8 L) and IRV (B, -0.4±0.6 L; LA, -1.5 to +0.8 L) within the pooled data from all 4 conditions. Exercise-induced changes in VE, VT, BF, IC and IRV recorded from HEXO and Ptach closely tracked each other. Conclusion: The Hexoskin biometric vest is a valid tool to monitor ventilatory responses during ADLs in COPD.