The Middle Bronze Age alphabets are two similar undeciphered scripts, dated to be from the Middle Bronze Age (2000-1500 BCE), and believed to be ancestral to nearly all modern alphabets:

• the Proto-Sinaitic script, discovered in Palestine and Sinai in the winter of 1904-1905 by William Matthew Flinders Petrie, and dated to 1500 BCE, and

• the Wadi el-Hol script, discovered in Middle Egypt in 1999 by John and Deborah Darnell and dated to 1800 BCE.

The Proto-Sinaitic script

The Proto-Sinaitic script is best known from carved graffiti in the Sinai peninsula, most famously from a mining area of the Sinai called Serabit el-Khadim (سرابيت الخادم). These mines were worked by prisoners of war from southwest Asia who presumably spoke a West Semitic language, such as the Canaanite that was ancestral to Phoenician. The Serabit el-Khadim inscriptions were found in a temple of Hathor (), and appear to be votive texts.

Despite a century of study, researchers can agree on the decipherment of only a single phrase, cracked in 1916 by Alan Gardiner: לבעלת (to the Lady) [ (Lady) being a title of Hathor and the feminine of the title (Lord) given to the Semitic god], although the word (loved) is frequently cited as a second word.

The script has graphic similarities with the Egyptian hieratic script, the less elaborate form of the hieroglyphs. In the 1950s and 60s it was common to show the derivation of the Canaanite alphabet from hieratic, using William Albright's interpretations of Proto-Sinaitic as the key. It was generally accepted that the language of the inscriptions was Semitic, that the script had a hieratic prototype and was ancestral to the Semitic alphabets, and that the script was itself acrophonic and alphabetic (more specifically, a consonantal alphabet or abjad). The word (Lady) lends credence to the identification of the language as Semitic. However, the lack of further progress in decipherment casts doubt over the other suppositions, and the identification of the hieratic prototypes remains speculative.

The Wadi el-Hol script

The Wadi el-Hol (Arabic وادي الحول 'Gulch of Terror') inscriptions were also carved in stone, along an ancient high-desert military and trade road linking Thebes and Abydos, in a wadi in the Qena bend of the Nile, at approx. . Two inscriptions are known in what appears to be a Semitic abjad, and there are dozens of other hieratic/hieroglyphic found at Wadi al-Hol as well. The script is graphically very similar to the Proto-Sinaitic inscriptions, but is older and further south, in the heart of literate Egypt. The shapes and angles of the glyphs best match hieratic graffiti from 2000 BCE, during the First Interdynastic Period. Frank M. Cross of Harvard University believes the inscriptions are "clearly the oldest of alphabetic writing", and are similar enough to later Semitic writing to conclude that "this belongs to a single evolution of the alphabet."
H₁ is a figure of celebration [Gardiner A28], whereas h₂ is either that of a child [Gardiner A17] or of dancing [Gardiner A32]. If the latter, h₁ and h₂ may be graphic variants (such as two hieroglyphs both used to write the Canaanite word hillul "jubilation") rather than different consonants.

Several scholars agree that the רב rb at the beginning of Inscription 1 is likely rebbe (chief; cognate with rabbi). Several scholars have also asserted that the אל ’l at the end of Inscription 2 is likely ’el "(a) god". Without cited sources, and lacking any clear reference to the actual texts, these comments should be held as conjecture.

Origin of alphabetic writing

The Egyptian hieroglyphic script was logosyllabic, that is, consisted of signs that stand for words, sounds, or place a word in a category. There was a complete set of uniliteral glyphs from at least 2700 BCEthat is, the hieroglyphic script contained an alphabetic subsystem (not including vowels) within it. While logographic systems such as Egyptian and Old Sumerian are extremely time-consuming to learn, they are sometimes considered superior to alphabets when it comes to reading. For literate Egyptians, whose livelihoods depended on their mastery of writing, there was little advantage to whittling the script down to a simple alphabet. Purely uniliteral (alphabetic) writing was used mainly to transcribe foreign names.

However, from the 22^nd to 20^th centuries BCE, central rule broke down. John and Debby Darnell found contemporary hieratic references to an Egyptian named "Bebi, General of the Asiatics".
They speculate that:

[Darnell] explains:

In other words, it was a utilitarian invention for soldiers and merchants. The assumption is that they developed a Semitic script based on acrophony, where the first sound of the Semitic name of an Egyptian glyph came to be the value of that glyph. Just as the numerals 1, 2, 3, etc. changed names but retained their graphic forms as they passed from India to Arabia to Europe, so the names of the letters were translated as they passed from the Egyptians to the Semites. For example, the name of the hieratic glyph for house changed from Egyptian pr to Canaanite bayt, and thus the glyph came to stand for /b/. House and most of the other letters were not uniliteral glyphs in Egyptian: the Semitic alphabet is not derived from the existing Egyptian alphabet, but rather from the full set of hieratic hieroglyphs. In fact, some of the letters, such as ה H, may have been determinatives (semantic complements), and thus had no sound value in Egyptian. However, the Semitic names are not attested until c. 200 BCE, and some scholars doubt that acrophony had anything to do with the invention of the alphabet.