4-HO-DET is a novel substituted tryptamine closely related to Psilocin and Psilocybin. It was invented in the 1950s by Albert Hofmann and Franz Troxler in the Sandoz lab under the lab code CZ-74. Together with its phosphoric acid ester 4-PO-DET (CEY-19), it was provided to German research scientists for testing and evaluation. (Leuner & Baer 1965). 4-HO-DET is also referred to as 4-Hydroxy-N, N –diethyltryptamine.
4-HO-DET belongs in a category called 4-substituted tryptamines, the classics of which include Psilocybin and Psilocin. Many such substitutions in this pattern have been developed, some of which have been studied and tested in various degrees.
A series of studies were conducted and published in the 1960s by Dr. Hanscarl Leuner and G. Baer, involving clinical trials with human volunteers (Leuner & Baer 1965; Baer 1967; Leuner 1962). These studies found that CZ-74 produced psychedelic effects that were similar and slightly differing from Psilocybin and LSD. Whilst the overall psychedelic effects were reported as similar to LSD, the primary differences were in duration and dosage.
The trials were done with a range of dosages. The established physical effects noticed, included slight increases in pulse rate, body temperature, and blood pressure, nausea, hypersalivation, mydriasis (dilation of pupils), somewhat increased reflexes, and disturbances in coordination.
Classic psychedelic effects similar to LSD, Psilocybin and Mescaline were noted, with the most frequent of effects being a distortion of body image, optical hallucinations and sensations. The second biggest group of effects reported were nausea, euphoria, dysphoria, clouding of consciousness, acoustic hallucinations, paranoid thoughts, time-distortion, mystical/cosmic experiences and age regression.
Rarely and only with the highest dosages used, were neurotic symptoms noticed. These included delirium, depersonalization, and paranoia (Baer 1967).
With respect to duration, 4-HO-DET exhibited a reduced duration 0f activity. It is characterized as being relatively abrupt in its comedown and duration, with less psychotomimetic effects in comparison with psilocybin.
In the late 1980s, Jochen Gartz, a colleague of the late Alexander Shulgin, discovered a novel means of synthesis of 4-PO-DET. P. Cubensis mushrooms were grown from a mycelia substrate supplemented with N,N – Diethyltryptamine (DET) HCl. Both 4-PO-DET and 4-HO-DET were isolated from the mushroom. 
In addition, it was found that the mushrooms yielded up to 3.3% alkaloid content by dried weight (whereas on average, the typical magic mushroom only contains 1-2% psilocin/psilocybin by dried weight). The ideal saturation was found to be 0.25 mmol per 13.5 grams of mycelial substrate. Spores for Psilocybe cubensis were inoculated into the substrate.
Gartz conducted further research by adding NMT (N-methyl-Tryptamine) to the substrate and found that it yielded mushrooms with exclusively 4-HO-NMT (4-hydroxy-N-methyltryptamine) and Baeocystin (4-PO-NMT, 4-phoshporyloxy-N-methyltryptamine).
Additionally, adding DPT (N,N–Dipropyltryptamine) to the substrate, yielded mushrooms with 4-HO-DPT/4-PO-DPT, whilst adding DiPT (N,N-Diisopropyltryptamine) to the substrate, yielded mushrooms with 4-HO-DiPT/4-PO-DiPT .
It was determined that the enzymes responsible for the biosynthesis of psilocin/psilocybin can recognize a potentially wide variety of tryptamines as enzymatic substrate, including synthetic tryptamines, and produce biosynthetic psilocin analogs as metabolites.
The fundamental route of biosynthesis typically being:
Tryptophan -> Tryptamine -> NMT/DMT -> 4-HO-NMT/psilocin- > baeocystin/psilocybin