The aim of this article is to discuss the lemmatisation process of Old English adverbs inflected for the superlative from a corpus-based perspective. This study has been conducted on the basis of a semi-automatic methodology through which the inflectional forms have been automatically extracted from The York-Toronto-Helsinki Parsed Corpus of Old English Prose and The York Toronto- Helsinki Parsed Corpus of Old English Poetry whereas the task of assigning a lemma has been completed manually. The list of adverbial lemmas amounts to 1,755 and has been provided by the lexical database of Old English Nerthus. Additionally, the resulting lemmatised list has been checked against the lemmatised forms compiled by the Dictionary of Old English and Seelig’s (1930) work on Old English comparative and superlative adjectives and adverbs. Through this comparison it has been possible to verify doubtful forms and incorporate new ones that are unattested by the YCOE. This pilot study has implemented for the first time a methodology for the lemmatisation of a non-verbal class and can be further applied to those categories that are still unlemmatised, namely nouns and adjectives.