This research aims to improve the accuracy and efficiency of Optical Character Recognition (OCR) technology for the Thai language, specifically in the context of Thai government documents. OCR enables the conversion of text from images into machine-readable format, facilitating document storage and further processing. However, applying OCR to the Thai language presents unique challenges due to its complexity. This study focuses on enhancing the performance of the Tesseract OCR engine, a widely used free OCR technology, by implementing various image preprocessing techniques such as masking, adaptive thresholds, median filtering, Canny edge detection, and morphological operators. A dataset of Thai documents is utilized, and the OCR system's output is evaluated using word error rate (WER) and character error rate (CER) metrics. To improve text extraction accuracy, the research employs the original U-Net architecture [19] for image segmentation. Furthermore, the Tesseract OCR engine is finetuned, and image preprocessing is performed to optimize OCR system accuracy. The developed tools automate workflow processes, alleviate constraints on model training, and enable the effective utilization of information from official Thai documents for various purposes.