Reverend Krzysztof Kluk was born in 1739 in Ciechanowiec, Podlasie region. He was a parson of the Ciechanowiec parish since 1770. He is the author of 14 volumes of works of natural science printed between 1777 and 1789 and a 372-page manuscript which was a draft of prepared sermons (here we can find loose insertions, mainly on farm topics). All studies were written during his stay in Ciechanowiec. Here he died in 1796. He wrote his works in Polish complying with grammar and spelling rules. Kluk's works are taken into account in studies about the history of the Polish language. However Kluk's creativity, especially in the part concerning the life and work of rural population had utilitarian and sometimes extremely practical character. Therefore, he used simple language that was understood by people to whom he addressed his works. His utterances often had a colloquial form, taken from the local language. These were agricultural terms, names of objects and activities, emotional words and many other words connected with everyday life and material culture of country people. Numerous examples of dialectal expressions used contemporarily in Ciechanowiec and the neighbourhood can be found in Kluk's writings. The dialectal layer in Krzysztof Kluk's heritage is not sufficiently researched or described. Krzysztof Kluk's works are a source of material - grammar features, phrases and most of all vocabulary common for all North-Eastern area of Polish. They can be found in 19th century dictionaries of this region as well as in dialectal material recorded even in the second half of the 20th century.