Ferrocenylnaphthalene diimide‐based electrochemical hybridization assay via a multi‐electrode chip was applied to detect the methylation frequency in the promoter region of human telomerase reverse transcriptase (hTERT) gene for clinical samples from tissues, local exfoliated oral cells from a lesion, or from entire oral cavity after their methylation specific PCRs. These methylation frequencies were increased with cancer progress as the following order: healthy volunteers, oral leukoplakia as precancerous lesion, and oral squamous cell carcinoma (OSCC). Operating characteristic analysis of the obtained current data doesn't only give excellent discrimination ability of OSCC, but also of oral leukoplakia from healthy volunteers for all samples. Sensitivity and specificity was 95 % and 90 %, respectively, which is a comparable with methods in practical use.