The Papers of Alexander Johnston consists of manuscripts written by Johnston, commissioned by him, or simply presented by him to the Society. These are:

• Portfolio of material donated by Sir Alexander Johnston to the Royal Asiatic Society
• 'A Summary of the Principle Evidence for the Truth, Divine Origin of the Christian Revelation' by Beilby, Lord Bishop of London, translated J.G. Philips & C. de Saram into Sinhalese.
• "Moses in the Bulrushes - A Sacred Drama" and "Joseph" by Hannah More, translations in Sinhalese.
• Report on tumuli or barrows in the Sardis region (Turkey) by George Hale.

A bound volume of manuscripts of various kinds given by Sir Alexander Johnston. The volume is in poor condition with the front board detached from the spine and the rear board missing. The cover bears a list of the manuscripts. These are:

• "A Vutteluttoo Syllabarium" - "a table of Vatteluttu script".
• "Vocabulary English and Cingalese which last is spoken in the Island of Ceylon" - an "English-Sinhalese vocabulary" presented to the Society by Johnston on 17 November 1827.
• "3 forms of the Singalese character used in writing Sanscrit, Pali and Singalese" - "Sinhalese-Pali alphabet"
• "Plan of a Comparative Vocabulary of Indian Languages; Read at the Literary Society of Bombay on the 26th May 1806 by Sir James Mackintosh". Printed, Bombay, 1806, presented to the Royal Asiatic Society by Johnston on 12 July 1828.
• "English-Sinhalese-Pali-Sanskrit vocabularies".
• "Vocabulary English and Cingalese which last is spoken on the Island of Ceylon" - an "English-Sinhalese vocabulary" presented to the Royal Asiatic Society by Johnston on 17 November 1827.
• "Vocabulary English and Pavly" - an "English-Pali vocabulary" presented to the Royal Asiatic Society by Johnston on 17 November 1827. Two manuscripts which also bear the name Mr. Burnouf.
• "Translation of a Sanscrit Inscription in Singhalese characters" - presented to the Royal Asiatic Society by Johnston on 17 November 1827. The description is dated April 1820 and bears the names of 3 contributors (difficult to decipher).
• "[This] translation you made at [j...] from the Sanscrit by the [Namma] of [Cunclasus]" - English translation concerning the whereabouts of someone who has gone to a hermitage.
• English-Sanskrit [?] vocabulary "In Sanscrit" - sheet of Sanskrit words.
• Paragraph of [Sinhalese] with "Honble Sir A. Johnston" on reverse. Sketch of a standing column.
• "Malabar Translation of the King of Achun's Pass for the [Gral] Ship, Allum Shah, [J D Lippiatt]
• "2 large & 2 small Cyngalese Alphabets Presented by Sir A Johnston Noy 17 1827"
• "1 Large & Small Cingalese Alphabet by Ahan de [Sarum] "Large & small Cingalese Alphabet" - these are on large sheets of paper which have been folded to fit the book.
• Burmese Alphabet.
• "Vocabulary English, Congalese and Pavly" - "English-Sinhalese-Pali- Sanskrit vocabularies" presented by Johnston 17 November 1827.
• "Maldive primer in Maldive script" - with note stating "The Maldive Alphabet as given in a MS presented to the RAS by Sir Alexander Johnston is writing from right to left and is evidently of Arabic origin." The pages are oversize and have been folded to fit the size of the book.
• Further Maldive vocabulary sheets.
• "This Book is called [Rayloe Rearyee]" - a booklet of alphabet and vocabulary in [Tamil] script.
• Vocabularies and alphabets in Maldive and roman script with Tamil translation
• "Letters from Sultan Muhammad Muin al-Din ibn Sikandar to the Governor of Ceylon on his coast in A.H.1227".
• "A prayer in Arabic." and "The above prayer translated into Booganese language & character by the Booganese [Hadgie]" - "Arabic prayer with translation into Bugis language in Bugis script"
• "Booganese Alphabet written by the Booganese [hadgie] on the [hare] Island the 19th of Nov 1815" - table of Bugis aphabet with key.
• "A Tamil Vocabulary" - "English-Tamil-Telugu vocabularies, mixed".
• "A Telugu Syllabarium" - "Telugug and Oriya alphabets", presented to the Royal Asiatic Society by Johnston on 3 March 1827.