After the simultaneous Invasion of Poland by Nazi Germany and the Soviet Union, Kępiński was captured and imprisoned in Hungary, to where he had fled.

[2] Later he was freed and moved to the United Kingdom, spending a short time with the Polish Air Force in Great Britain.

[2] Due to his involvement, in the 1950s, in the rehabilitation programme for former concentration camp inmates, Kępiński may be regarded as the pioneer of the PTSD research.

As noted by psychiatrist Krzysztof Rutkowski, the same syndrome was later investigated in other countries (for example in the United States after the Vietnam War in the 1970s), and is currently known as the post-traumatic stress disorder.

[6] Co-workers and biographers of Kępiński emphasize that the key characteristic of his professional activity was his unique approach to the patient, inspired by the philosophy of dialogue.

In his view, diagnosis and therapy should not be based solely on logical analysis, as the inclusion of the emotional dimension is indispensable in psychology.

The general attitude of the therapist should encourage the patient to share experiences, feelings and thoughts without the fear of being judged.

Wearing masks, assuming the position of superiority and being inauthentic during the therapeutic interaction are the most significant mistakes made by therapists.

According to that view, psychosis may be seen as distortions of the hierarchy of values which is one of the key aspects of the information metabolism process occurring in the organism of the patient.

[4] He contended that therapeutic work could lead to the formation of a healthy hierarchy of values, allowing the patient to interact with reality in a more balanced manner.

[12] In his books, Kępiński explained various mental conditions as disorders and imbalances of the information metabolism in general and its inherent value structure in particular.

As a young medic, Kępiński was drawn to the works of Carl Jung and subjected the more "mystical" aspects to a critique which inspired him to launch on his own clinical and philosophical quest.

On the other hand, he was skeptical about methods and theories which lacked a sufficiently solid scientific basis, e.g. psychoanalysis, and rejected various forms of what he dismissed as "magical thinking" in psychology.

[15] Kępiński argued that human ethics are not socially-constructed but rooted in biology and their prerequisites can be found in the animal world.

[8] Kępiński's disciple - psychiatrist Jacek Bomba - noted that the greatest value of his information metabolism theory is its quality of being an accurate and comprehensive synthesis of knowledge from neurophysiology, psychology, social science and medicine.