en گروه سرامیک Ceramic Materials and Engineering Research Paper Research Paper <em>The aim of the present study is to assess the hardness, corrosion, and cytotoxicity of a commercially available cobalt-chromium (Co-Cr) alloy before and after simulated heat treatments at porcelain firing temperature. Five Co-Cr samples were fabricated using lost wax casting procedure. Heat treatments were carried out at 650&deg;C, 750&deg;C, 850&deg;C, and 950&deg;C. Vickers hardness was measured for as-cast and heat treated samples. The corrosion test was carried out separately in 0.1 N NaCl, 1% citric acid and artificial saliva at room temperature using potentiodynamic polarization technique. Gingival tissue biopsy of patients was taken and cultured to measure the cell viability by MTT colorimetric assay. Lowest hardness was observed at 650&deg;C. 0.1 N NaCl and 1% citric acid corrosion medium showed a similar trend of corrosion rate. </em><em>The least corrosion rate was found in artificial saliva</em><em>. Firing temperature has an impact on the physical, chemical and biological properties of Co-Cr alloy in long-term clinical use.</em> Cobalt-chromium, Heat treatment, Corrosion, Cytotoxicity, Hardness 36 42 http://ijmse.iust.ac.ir/browse.php?a_code=A-10-2025-1&slc_lang=en&sid=1 V. Dave vkdave95@gmail.com 1800319475328460010251 1800319475328460010251 No Department of Dental Materials, Manipal College of Dental Sciences, Mangalore R. Kotian ravindra.kotian@manipal.edu 1800319475328460010252 1800319475328460010252 Yes Department of Dental Materials, Manipal College of Dental Sciences, Mangalore P. Madhyastha prashanthi.madhyast@manipal.edu 1800319475328460010253 1800319475328460010253 No Department of Dental Materials, Manipal College of Dental Sciences, Mangalore K. Boaz karen.boaz@manipal.edu 1800319475328460010254 1800319475328460010254 No Department of Oral Pathology and Microbiology, Manipal College of Dental Sciences, Mangalore P. Rao padmalatha.rao@manipal.edu 1800319475328460010255 1800319475328460010255 No Department of Chemistry, Manipal Institute of Technology, Manipal B.P. Charitha charithabp2014@gmail.com 1800319475328460010256 1800319475328460010256 No School of Graduate Sciences, Jain University.