The semi-detached eclipsing binary system CF Puppis ( P=7.65 days) has been analysed using the Wilson–Devinney program. Light curves have been obtained in the G eneva 7-colour photometric system, and radial velocity curves for both components have been measured with the cross-correlation technique. The physical and orbital parameters have been determined through a self-consistent simultaneous solution of light curves in seven colours and of the radial velocity curves of both components. The absolute elements of the components are, for the primary (mass gainer), M 1=1.84±0.04 M ⊙, R 1=3.06±0.01 R ⊙, M bol 1 =1.74±0.02, T eff 1 =6671±27 K, and for the secondary (mass loser), M 2=0.38±0.01 M ⊙, R 2=5.39 R ⊙, M bol 2 =2.51±0.02, T eff 2 =4202±17 K. The semi-major axis A of the relative orbit is 21.28±0.15 R ⊙. The estimated spectral types of the components are about F3 IV (primary) and K2/3 III. CF Pup has one of the coolest component A among the Algol systems. The equatorial rotational velocities are 24.8 (primary) and 37.0 km s −1. The secondary is clearly synchronized, and the primary is nearly synchronized ( v syn=20.2 km s −1). The distance to CF Pup is evaluated to 506 ± 16 pc, and the colour excess EB2-V1 to 0.033 ± 0.017.