Objective: Loneliness has become an increasingly common phenomenon due to lockdowns put in place to minimize spread of COVID-19. The current body of literature suggests the relationship between...Show moreObjective: Loneliness has become an increasingly common phenomenon due to lockdowns put in place to minimize spread of COVID-19. The current body of literature suggests the relationship between loneliness and various Big-5 personality dimensions, except openness to experience. The current study aimed to fill this gap by investigating if there is a predictive effect of 1) openness to experience and 2) tolerance to uncertainty on loneliness during COVID-19 pandemic. It also aimed to investigate if this relation is influenced by gender. Methods: Responses from 349 participants were collected in anonymous online surveys at the Central Institute of Mental Health in Mannheim and at Leiden University. The survey was posted at online platforms and distributed amongst social media and the University Research Systems. Openness was assessed with the 10-Item Big Five Inventory (BFI10). Loneliness was measured with UCLA loneliness scale (ULS8). Intolerance of uncertainty was assessed with the Intolerance of Uncertainty Scale (UI18). Results: The results showed that higher BFI10 scores predicted higher ULS8 scores (loneliness) (B = .066, SE= .031, p =.036, 95% CI= [.004, .128]). Similarly, higher UI18 scores (intolerance of uncertainty) predicted higher scores on ULS8 (loneliness) (B = .298 , SE= .036, p =<.001, 95% CI= [.228, .369]). There was no significant effect of gender on loneliness. Conclusions: Our results show the importance of the personality trait openness and intolerance of uncertainty in predicting loneliness during the COVID-19 pandemic. Further investigation is is important to study this relationship using longitudinal designs and accounting for other personality characteristics.Show less