The objective of this study was to investigate the condensation heat transfer characteristics of a high-temperature heat pump condenser. To this end, condensation heat transfer experiments were conducted in a plate-fin heat exchanger at high temperatures using R1234ze(Z), which has a relatively high critical temperature. The experiments were performed with two types of fins (serrated fin and plane fin) and two cooling methods (one-side cooling and both cooling). In the case of one-side cooling, condensation was observed through a glass window. Consequently, the heat transfer coefficient exhibited an increase in the high-quality region due to the stirring of the refrigerant liquid phase at the serrated portion of the serrated fins. However, a decrease was observed in the medium-quality region due to the homogenization of the refrigerant liquid film thickness at the serrated portion. At saturated temperatures above 0.8 reduced pressure, the stirring effect of the serrate is no longer observed, and the heat transfer coefficient at high quality becomes low. Furthermore, the heat transfer coefficient is also reduced at saturated temperatures above the reduced pressure of 0.8.