Objective: to test the clinimetric properties of the HACOR scale in adult patients using NIV in a hospital emergency department. Methods: HACOR scale considers heart rate (HR), acidosis (blood pH), consciousness level (Glasgow scale), oxygenation (PaO₂/FiO₂), and respiratory rate (RR), from 0 to 25 points, the highest score defines the need for intubation (mechanic ventilation-MV) after an hour NIV intervention in hospitalized hypoxemic patients. Ten minutes later, the second application of HACOR scale was performed to test reliability (Intraclass Correlation Coefficient-ICC), measurement error (standard error of measurement-SEM and minimum difference detected-MMD), ceiling and floor effects, construct validity by correlation (Pearson-r) with pulse oxygen saturation (SpO₂) and predictive ability (area under the curve-ROC). Results: 56 patients were included (58.8±17.8 yrs; SAPS III: 55.7±14.3 pts; 29% with acute lung edema and 11% on thoracoabdominal postoperative period). After 1h of NIV, patients had HR=100±24 bpm, pH=7.4±0.8, Glasgow scale=14±1 pt, PaO₂/FiO₂=232±123 and HACOR=3.3±3.5 pt. The clinimetric properties are showed on Table 1. Eleven patients required MV and 23 patients died. Conclusion: The HACOR scale has adequate clinimetric properties, however, it showed a floor effect in the sample included in this study.