Introduction: Acidosis is a process causing increased acidity in the blood and other body tissues (i.e., an increase in hydrogen ion concentration). If not further qualied, it usually refers to acidity of the blood plasma Acidemia is said to occur when arterial pH falls below 7.35 , while its counterpart (alkalemia) occurs at a pH over 7.45. Arterial blood gas analysis and other tests are required to separate the main causes.Aims: To nd out correlation between different grades of Acidemia with 30 day mortality of patient diagnosed as academic in emergency department Materials and method: This was a single center observational, retrospective cohort study from tertiary care hospital in Kolkata, India from January 2021 – January – 2022. All Patients were presenting with signs of Acidemia in Emergency Department. Age >18 years, Blood gas analysis, Done in ED and pH ≤ 7.34 were included in this study. Result: In mortality, 33(32.4%) patients were in <7.0 PH group, 31(30.4%) patients were in 7.0-7.10 PH group, 23 (22.5%) patients were in 7.11-7.20 PH group and 15 (14.7%) patients were in 7.21-7.34 PH group. Association of PH group with Mortality was statistically signicant (p<0.0001). In without Mortality, the mean Age (mean± s.d.) of patients was 57.0268 ±9.2811. In with Mortality, the mean Age (mean± s.d.) of patients was 56.2549±9.0758. Distribution of mean Age with Mortality was not statistically signicant (p=0.4506). In without Mortality, the mean PH (mean± s.d.) of patients was 7.1898 ±.1189. In with Mortality, the mean PH (mean± s.d.) of patients was 6.9708 ±.2907. Distribution of mean PH with Mortality was statistically signicant (p<0.0001). In without Mortality, the mean Hospital Stay (mean± s.d.) of patients was 14.1512 ±5.5302. In with Mortality, the mean Hospital Stay (mean± s.d.) of patients was 7.4804 ±6.1010. Distribution of mean Hospital Stay with Mortality was statistically signicant (p<0.0001). Conclusion: Patients presenting in emergency with low PH (acidemia) require immediate management and hospitalization for better outcome.