James Charlesworth writes (The Pseudepigrapha and Modern Research, p. 106):
Extant in Hebrew is a pseudepigraphon called 3 Enoch, which was edited and translated into English by H. Odeberg (no. 808; see the favorable review by R. Bultmann in TLZ 62  cols. 449-53). He concludes that while the main body (chps. 3-48A) and its redaction date from the second half of the third century (p. 41), some portions (48B and C, 1 and 2) are later, and others (3-15) go back to the second or first century A.D. (pp. 42, 79, 83, 188).
3 Enoch contains 48 chapters: R. Ishmael ben Elisha's ascension and vision of the Merkabah (1-2); concerning Metatron, the Prince of the Presence, who is also Enoch (3-16); angelology (17-28:6); divine judgment and the heavenly tribunal (28:7-33:2); the Merkabah phenomena (33:3-40); Metatron reveals secrets to R. Ishmael (41-48A); divine names (48B); an Enoch-Metatron section (48C); names of Metatron (48D).
This pseudepigraphon should be considered for inclusion within the Pseudepigrapha. The work is Jewish, and at least portions of it predate A.D. 200. The form and content are related, at least intermittently, to the Old Testament, and the book is heavily influenced by the apocalyptic genre, showing impressive relationships with 1 and 2 Enoch. It is attributed pseudonymously to an Old Testament figure.
P. Alexander writes: "It is impossible to reach a very firm conclusion as to the date of 3 Enoch. The main problem is the literary character of the work: it is not the total product of a single author at a particular point in time, but the deposit of a 'school tradition' which incorporates elements from widely different periods. Certain rough chronological limits can, however, be established. (1) 3 Enoch can hardly have been written later than the tenth century A.D., since it is clear from the writings of Sa'adya, Sherira and Hai, and the Karaites Jacob al-Qirqisani and Salmon b. Yeruhim that the Merkabah literature was circulating widely among Rabbanites at that period and was regarded as being of considerable antiquity and authority. Particularly interesting is the fact that Jacob al-Qirqisani knew the short account of the elevation of Enoch found in certain recensions of the Alphabet of Aqiba and in 3 Enoch 48C (Kitab al-Anwar 1.4.2, ed. Nemoy, vol. 1, p. 31, 15). This short account appears to be a summary of a longer version of the elevation of Enoch closely akin to 3 Enoch 3-15. (2) If we are right in surmising that 3 Enoch has drawn some of its materials from the Babylonian Talmud, then its final redaction can hardly be earlier than the fifth century A.D. (3) The magical bowls from Nippur show that many of 3 Enoch's ideas about Metatron and about the heavenly world were known in magical circles in the sixth and seventh centuries A.D. All things considered, then, though 3 Enoch contains some very old traditions and stands in direct line with developments which had already begun in the Maccabean era, a date for its final redaction in the fifth or the sixth century A.D. cannot be far from the truth." (The Old Testament Pseudepigrapha, vol. 1, pp. 228-229)
Please buy the CD to support the site, view it without ads, and get bonus stuff!