Apparatus for the finishing of yarns, comprising: a feeding station for at least one yarn to be treated for feeding said yarn along a line of advance; a collection station for said yarn located downstream of the line of advance; and distribution means for distributing a finishing additive on said yarn, said distribution means being arranged along the line of advance and comprising at least one dispensing device for said finishing additive characterised by said dispensing device having a chamber for the passaging of the yarn defining an opening input for the yarn inside the chamber and an outlet opening for the yarn to which the additive has been distributed; at least one tensioning device associated to the yarn to stretch the yarn along the line of advance to a predetermined tensioning value as a function of the features and dimensions of the yarn; said tensioning device comprising at least one restraining roller around which the yarn is partially wrapped upstream of the line of advance, and means for detecting and adjusting the resistance of the roller to determinate said predetermined tensioning value; said roller implementing a resistance to the advance of the Z yarn towards the collection station according to said predetermined tensioning value; said dispensing device further comprising a plurality of spraying nozzles arranged within said chamber for the passaging of the yarn to distribute a jet of additive on the yarn fed continuously, whereby said dispensing device comprises further a support member for said nozzles, movable inside the chamber to direct the jet of additive towards the yarn intermittently; said support member comprising a rotary drum rotatable about a rotation axis transverse to the line of advance of the yarn; said nozzles being arranged on a peripheral area of the drum. a feeding station for at least one yarn to be treated for feeding said yarn along a line of advance; a collection station for said yarn located downstream of the line of advance; and distribution means for distributing a finishing additive on said yarn, said distribution means being arranged along the line of advance and comprising at least one dispensing device for said finishing additive characterised by said dispensing device having a chamber for the passaging of the yarn defining an opening input for the yarn inside the chamber and an outlet opening for the yarn to which the additive has been distributed; at least one tensioning device associated to the yarn to stretch the yarn along the line of advance to a predetermined tensioning value as a function of the features and dimensions of the yarn; said tensioning device comprising at least one restraining roller around which the yarn is partially wrapped upstream of the line of advance, and means for detecting and adjusting the resistance of the roller to determinate said predetermined tensioning value; said roller implementing a resistance to the advance of the Z yarn towards the collection station according to said predetermined tensioning value; said dispensing device further comprising a plurality of spraying nozzles arranged within said chamber for the passaging of the yarn to distribute a jet of additive on the yarn fed continuously, whereby said dispensing device comprises further a support member for said nozzles, movable inside the chamber to direct the jet of additive towards the yarn intermittently; said support member comprising a rotary drum rotatable about a rotation axis transverse to the line of advance of the yarn; said nozzles being arranged on a peripheral area of the drum.