Richet held a deep interest in extrasensory perception and hypnosis.
In 1884, Alexandr Aksakov interested him in the medium of Eusapia Palladino.
In 1891, Richet founded the Annales des sciences psychiques.
He kept in touch with renowned occultists and spiritualists of his time such as Albert von Schrenck-Notzing, Frederic William Henry Myers and Gabriel Delanne.
In 1919, Richet became honorary chairman of the Institut Métapsychique International in Paris, and, in 1930, full-time president.

As a scientist, Richet was positive about a physical explanation for paranormal phenomena.
He wrote:  "It has been shown that as regards subjective metapsychics the simplest and most rational explanation is to suppose the existence of a faculty of supernormal cognition ... setting in motion the human intelligence by certain vibrations that do not move the normal senses."
In 1905, Richet was named president of the Society for Psychical Research in the United Kingdom.

In 1894, Richet coined the term ectoplasm.
Richet believed that some mediumship could be explained physically due to the external projection of a material substance (ectoplasm) from the body of the medium, but denied this substance had anything to do with spirits.
He rejected the spirit hypothesis of mediumship as unscientific, instead supporting the sixth sense hypothesis.
According to Richet:
It seems to me prudent not to give credence to the spiritistic hypothesis... it appears to me still (at the present time, at all events) improbable, for it contradicts (at least apparently) the most precise and definite data of physiology, whereas the hypothesis of the sixth sense is a new physiological notion which contradicts nothing that we learn from physiology.
Consequently, although in certain rare cases spiritism supplies an apparently simpler explanation, I cannot bring myself to accept it.
When we have fathomed the history of these unknown vibrations emanating from reality – past reality, present reality, and even future reality – we shall doubtless have given them an unwonted degree of importance.
The history of the Hertzian waves shows us the ubiquity of these vibrations in the external world, imperceptible to our senses.

He hypothesized a "sixth sense", an ability to perceive hypothetical vibrations, which he discussed in his 1928 book Our Sixth Sense.
Although he believed in extrasensory perception, Richet did not believe in life after death or spirits.

He investigated and studied various mediums such as Eva Carrière, William Eglinton, Pascal Forthuny, Stefan Ossowiecki, Leonora Piper and Raphael Schermann.
From 1905–1910, Richet attended many séances with the medium Linda Gazzera claiming she was a genuine medium who had performed psychokinesis, i.e. that various objects had been moved in the séance room.
Gazzera was exposed as a fraud in 1911.
Richet was also fooled into believing Joaquin María Argamasilla, known as the "Spaniard with X-ray Eyes", had genuine psychic powers, whom Harry Houdini exposed as a fraud in 1924.
According to Joseph McCabe, Richet was also duped by the fraudulent mediums Eva Carrière and Eusapia Palladino.

Historian Ruth Brandon also criticized Richet as credulous when it came to psychical research, noting "his will to believe, and his disinclination to accept any unpalatably contrary indications".
Richet held a deep interest in extrasensory perception and hypnosis. In 1884, Alexandr Aksakov interested him in the medium of Eusapia Palladino. In 1891, Richet founded the Annales des sciences psychiques. He kept in touch with renowned occultists and spiritualists of his time such as Albert von Schrenck-Notzing, Frederic William Henry Myers and Gabriel Delanne. In 1919, Richet became honorary chairman of the Institut Métapsychique International in Paris, and, in 1930, full-time president.
As a scientist, Richet was positive about a physical explanation for paranormal phenomena. He wrote:  "It has been shown that as regards subjective metapsychics the simplest and most rational explanation is to suppose the existence of a faculty of supernormal cognition ... setting in motion the human intelligence by certain vibrations that do not move the normal senses." In 1905, Richet was named president of the Society for Psychical Research in the United Kingdom.
In 1894, Richet coined the term ectoplasm. Richet believed that some mediumship could be explained physically due to the external projection of a material substance (ectoplasm) from the body of the medium, but denied this substance had anything to do with spirits. He rejected the spirit hypothesis of mediumship as unscientific, instead supporting the sixth sense hypothesis. According to Richet:
It seems to me prudent not to give credence to the spiritistic hypothesis... it appears to me still (at the present time, at all events) improbable, for it contradicts (at least apparently) the most precise and definite data of physiology, whereas the hypothesis of the sixth sense is a new physiological notion which contradicts nothing that we learn from physiology. Consequently, although in certain rare cases spiritism supplies an apparently simpler explanation, I cannot bring myself to accept it. When we have fathomed the history of these unknown vibrations emanating from reality – past reality, present reality, and even future reality – we shall doubtless have given them an unwonted degree of importance. The history of the Hertzian waves shows us the ubiquity of these vibrations in the external world, imperceptible to our senses.
He hypothesized a "sixth sense", an ability to perceive hypothetical vibrations, which he discussed in his 1928 book Our Sixth Sense. Although he believed in extrasensory perception, Richet did not believe in life after death or spirits.
He investigated and studied various mediums such as Eva Carrière, William Eglinton, Pascal Forthuny, Stefan Ossowiecki, Leonora Piper and Raphael Schermann. From 1905–1910, Richet attended many séances with the medium Linda Gazzera claiming she was a genuine medium who had performed psychokinesis, i.e. that various objects had been moved in the séance room. Gazzera was exposed as a fraud in 1911. Richet was also fooled into believing Joaquin María Argamasilla, known as the "Spaniard with X-ray Eyes", had genuine psychic powers, whom Harry Houdini exposed as a fraud in 1924. According to Joseph McCabe, Richet was also duped by the fraudulent mediums Eva Carrière and Eusapia Palladino.
Historian Ruth Brandon also criticized Richet as credulous when it came to psychical research, noting "his will to believe, and his disinclination to accept any unpalatably contrary indications".
Charles Richet