AbstractIntroduction There is a dearth of comprehensive studies on the association between serum electrolyte and adverse short-term prognosis of Chinese patients with acute decompensated heart failure (ADHF).Patients and methods A total of 5166 patients with ADHF were divided into four serum electrolyte-related study populations (potassium (n = 5145), sodium (n = 5135), chloride (n = 4966), serum total calcium (STC) (n = 4143)) under corresponding exclusions. Different logistic regression models were utilized to gauge the association between these electrolytes or the number of electrolyte abnormalities and the risk of a composite of all-cause mortality or 30-day heart failure (HF) readmission.Results In multivariable adjusted analysis, patients with potassium below 3.5 mmol/L (odds ratios (ORs) 1.45; 95% confidence interval (CI):1.07–1.95), 4.01–4.50 mmol/L (OR: 1.29, CI: 1.02–1.62), 4.51–5.00 mmol/L (OR: 1.43, CI: 1.08–1.90) and above 5.00 mmol/L (OR: 1.74, CI: 1.21–2.51) had an increased risk of outcome when compared with potassium at 3.50–4.00 mmol/L. Sodium levels were inversely related to the risk of a composite outcome (