After returning to West Germany in December 1953, he developed data processing systems, contributed to early commercial applications of computer science and coined the German term "Informatik".

He worked full-time at the Bund der technischen Angestellten und Beamten (Butab), a federation for technical staff and officials of the social democratic trade union in Berlin.

A report stated that he, his wife Irmgard, Wernher von Braun, and his colleague Klaus Riedel were said to have expressed regret at an engineer's house one evening that they were not working on a spaceship and that they felt the war was not going well; this was considered a "defeatist" attitude.

92-101  Gröttrup worked under the supervision of Sergei Korolev and Boris Chertok who reported to the Soviet military government of Maj. Gen. Lev Gaidukov and Dmitry Ustinov, the Minister of Armaments.

[8] From 1946 until September 1950, Gröttrup headed the more than 170 German specialists working in Podlipki in the north east section of Moscow as part of Korolev's NII-88 and in Branch 1 of NII-88 on Gorodomlya Island in Lake Seliger.

However, the theoretical work of the German scientists proposed improved solutions due to lack of material, and new ideas significantly contributed to the later success of Soviet space program.

[15] The launcher for Sputnik 1's orbital flight in October 1957 was based on R-7 Semyorka with a bundling (packeting) of a total of 20 engines with conical rocket bodies, as already proposed by the German scientists in 1949 in Gorodomlja.

For political reasons, however, the contributions made by the German collective of rocket scientists to Soviet missile development have long been considered insignificant by the public in East and West.

Fritz Karl Preikschat, who managed the high frequency lab under Gröttrup from 1946-1952 on Gorodomlya Island, and several other specialists made it to West Germany, and were interrogated as "defectors" by the CIA and MI6 (as part of the operation "Dragon Return" on the Soviet rocketry program.

In February 1967, Gröttrup introduced the idea of incorporating an integrated circuit chip onto a plastic carrier and filed the patent DE1574074[23] in West Germany for a tamper-proof identification switch based on a semiconductor device.

In September 1968, Gröttrup, together with Jürgen Dethloff as an investor, filed further patents for this identification switch, first in Austria[27] and in 1969 as subsequent applications in West Germany (DE1945777),[28] the United States (US3678250[29] and US3678250[30]), Great Britain (GB1317915[31] and GB1318850[32]), and other countries.

Gröttrup was managing director in charge of developing machine-readable security features to prevent counterfeit money together with half- and fully automated banknote processing systems (such as ISS 300 and ISS/BPS 3000).