This article examines how motivation affects peer review acceptance of journal manuscripts among German professors of biology, business administration, mechanical engineering, and sociology. Data collected via an online survey (March-May 2022) tested hypotheses based on self-determination theory. The results show significant discipline-specific differences. In the soft disciplines, intrinsic motivation, own manuscript submissions (reciprocity), and external motivation positively influenced peer review acceptance, while the motive to discover something new had a negative effect. In the hard disciplines, only sense of obligation to the scientific community was significant. Staff support positively influenced peer review acceptance in soft disciplines. The control variables revealed that the total number of peer review requests was positively related to acceptance. However, age, gender, departmental budget linked to publications, and academic discipline were not significant factors. These findings deepen our understanding of motivational factors in peer review and highlight important disciplinary differences.