We analyse the kinematical and dynamical state of the galaxy cluster RXCJ1230.7+3439, at z=0.332, using 93 new spectroscopic redshifts of galaxies acquired at the 3.6m TNG telescope and from SDSS DR16 public data. We find that RXCJ1230 appears as a clearly isolated peak in the redshift space, with a global line-of-sight velocity dispersion of 1004+147−122 km/s, and showing a very complex structure with the presence of three subclusters. Our analyses confirm that the three substructures detected are in a pre-merger phase, where the main interaction takes place with the south-west subclump. We compute a velocity dispersion of σv about 1000 and 800 km/s for the main cluster and the south-west substructure, respectively. The central main body and south-west substructure differ by about 870 km/s in the LOS velocity. From these data, we estimate a dynamical mass of M200=9.0+/-1.5e14 Msun and 4.4+/-3.3e14 Msun for the RXCJ1230 main body and south-west clump, respectively, which reveals that the cluster will suffer a merging characterized by a 2:1 mass ratio impact. We solve a two-body problem for this interaction and find that the most likely solution suggests that the merging axis lies almost contained in the plane of the sky and the subcluster will fully interact in about 0.3 Gyr. The comparison between the dynamical masses and those derived from X-ray data reveals a good agreement within errors (differences about 15%), which suggests that the innermost regions (<r500) of the galaxy clumps are almost in hydrostatical equilibrium. To summarize, RXCJ1230 is a young but also massive cluster in a pre-merging phase accreeting other galaxy systems from its environment.