A compression forming process of objects made of compact thermoplastic material, by means of a die comprising: a bottom die having a die cavity suitable for containing a batch of material in a form of small pieces, delimited by a lower internal surface facing upwards, which defines a lower base of the cavity, and by a lateral internal surface facing towards the central zone of the cavity, a punch, mobile with respect to the bottom die, having an internal surface (21, 31) facing downwards, which defines an upper base of the cavity, the lower internal surface and upper internal surface (21, 31) being opposite and neared to one another during step b), an air escape route from the bottom die, defined at a peripheral zone of the punch where the punch, at the end of step b), closes the bottom die cavity, defining the forming chamber, the process comprising following steps: a) inserting a batch of material in a form of small pieces in the cavity of the bottom die b) nearing the two parts of the die to one another, reducing a volume of the cavity up to a minimum amount in which a forming chamber is defined that determines the shape of the object, c) supplying heat to the particles of the batch, during step b), by heating the internal surfaces of the chamber of the bottom die and the punch with which the particles come into contact, increasing a degree of fluidity thereof with growing values over a period of time, starting from a minimum value at the start of step b) up to a maximum amount, at the end of step b), wherein step c) further comprises heating the particles of the batch in a differentiated way such that the particles situated near the upper internal surface (21, 31) are brought to values of fluidity, growing over time, with a delay with respect to particles located at the lower internal surface. a bottom die having a die cavity suitable for containing a batch of material in a form of small pieces, delimited by a lower internal surface facing upwards, which defines a lower base of the cavity, and by a lateral internal surface facing towards the central zone of the cavity, a punch, mobile with respect to the bottom die, having an internal surface (21, 31) facing downwards, which defines an upper base of the cavity, the lower internal surface and upper internal surface (21, 31) being opposite and neared to one another during step b), an air escape route from the bottom die, defined at a peripheral zone of the punch where the punch, at the end of step b), closes the bottom die cavity, defining the forming chamber, the process comprising following steps: a) inserting a batch of material in a form of small pieces in the cavity of the bottom die b) nearing the two parts of the die to one another, reducing a volume of the cavity up to a minimum amount in which a forming chamber is defined that determines the shape of the object, c) supplying heat to the particles of the batch, during step b), by heating the internal surfaces of the chamber of the bottom die and the punch with which the particles come into contact, increasing a degree of fluidity thereof with growing values over a period of time, starting from a minimum value at the start of step b) up to a maximum amount, at the end of step b), wherein step c) further comprises heating the particles of the batch in a differentiated way such that the particles situated near the upper internal surface (21, 31) are brought to values of fluidity, growing over time, with a delay with respect to particles located at the lower internal surface. a) inserting a batch of material in a form of small pieces in the cavity of the bottom die b) nearing the two parts of the die to one another, reducing a volume of the cavity up to a minimum amount in which a forming chamber is defined that determines the shape of the object, c) supplying heat to the particles of the batch, during step b), by heating the internal surfaces of the chamber of the bottom die and the punch with which the particles come into contact, increasing a degree of fluidity thereof with growing values over a period of time, starting from a minimum value at the start of step b) up to a maximum amount, at the end of step b), wherein step c) further comprises heating the particles of the batch in a differentiated way such that the particles situated near the upper internal surface (21, 31) are brought to values of fluidity, growing over time, with a delay with respect to particles located at the lower internal surface.