Abstract Body (Do not enter title and authors here): Introduction: Heart failure is associated with reduced cardiac output and cerebral hypoperfusion, which may disrupt neural activity in the brain. Resting electroencephalography (EEG) directly measures neural activity in the brain, however few studies have examined EEG measurements in individuals with heart failure. Research question: Our study aimed to address this gap in the literature by using high-density EEG to investigate resting neural activity in individuals with heart failure. Methods: Resting-state EEG was recorded from 13 individuals with heart failure (New York Heart Association class II-III) and 13 age- and sex- matched controls using a 128-electrode array. We calculated five EEG outcome measures in both sensor and source space: periodic alpha and beta power, dominant frequency, offset and slope. Mann-Whitney U tests were used to evaluate group differences in the global average of the main outcomes. Statistical comparisons EEG outcomes conducted using permutated-based Analysis of Covariance controlling for age and sex. Significance was set to p < 0.05 (corrected for multiple comparisons using FDR). Results: We found significant reductions in beta power and dominant frequency in the heart failure group in both sensor and source space. The grand average beta power across 128 electrodes for the heart failure group was 0.36 Hz (±0.07) and 0.49 (±0.11) for the control group and this was significantly different between groups (U = 25.00, z = -3.05, p = 0.003). Source space analysis revealed significant reductions in beta power in 50 out of 64 cortical regions examined. For dominant frequency in sensor space, the grand average dominant frequency across 128 electrodes for the heart failure group was 8.60 Hz (± 0.77) and 9.75 Hz (± 1.35) for the control group and this was significantly different between groups (U = 36.00, z = -2.49, p = 0.012). Source space analysis found reduced dominant frequency in the heart failure group in 30 of the 64 cortical regions assessed. No significant between group differences were found for alpha power, offset and slope. Conclusions: Our findings revealed widespread reductions in beta power and dominant frequency, suggesting disrupted cortical activity which may underlie impairments in cognitive and sensorimotor function in individuals with heart failure.