Purpose: The purpose of this paper is to analyse a programme designed to welcome and train new employees, implemented in a chemical industry, privileging the transmission of know-how as a dynamic process where learning is co-constructed in the course of the activity. Design/methodology/approach: The design of the programme was based on the analysis of the work performed in real context by operators and supervisors. The data about the programme's evaluation were collected by questionnaire, assessing the trainees' global development and the impact of the training programme (after six months). Findings: This paper involves designing, planning and implementing "4 × 4 Training", a training programme for young trainees. Combining in-class training with an extensive component of on-the-job mentoring, the programme involved trainees, mentors and internal trainers, monitored by work psychologists. The results show both the trainees and the mentors evaluate the programme positively. The professional transmission stands out as an activity that is thought through and defined in group, assisted by a mentoring relationship of mutual learning. Practical implications: When planning and developing intergenerational transmission processes, it is crucial to consider the organisational conditions, to involve from an early stage the key players of each work situation and to guarantee that the mentoring activity and the productive activity overlap coherently. Originality/value: It is an innovative process to integrate trainees in the chemical industry in Portugal. The methodological approach and the findings provide a first framework that justifies the relevance of the transmission of know-how through a real work situation.