Background: Selection of correct core material is vital for the success of endodontic treatment. Degree of conversion and microleakage of two bulkcure core build up materials was assessed. The two materials were different in their mode of curing; one was a light cure and the other a dual cure material. Aims: To evaluate and compare the degree of conversion and micro leakage of two bulkcure core build-up materials at various cavity depths. Settings and Design: In vitro- study. Methods and Material Seventy two extracted premolars and molars were divided into six groups (n=12). The teeth were accessed and sectioned with carborundum disc below CEJ junction. Etching and bonding of all samples was done. In Group1, 2 and 3 bulkcure core build- up material Photocore was placed at depths of 4mm, 6mm, 8mm respectively. In Group 4, 5 and 6 bulkcure core build- up material Luxacore was placed at depths of 4mm, 6mm, 8mm respectively. Degree of conversion of all samples was evaluated by using FTIR-ATR spectroscopy, Microleakage evaluation was done by dye penetration method. Statistical analysis: Data was analyzed by ANOVA and t test for FTIR-ATR evaluation for degree of polymerization. Chi-Square Test was used for microleakage analysis. Results: There is no significant difference between mean values of degree of conversion of Clearfil Photocore Group 1, 2, 3 compared together. (p=0.1115). There is a significant difference between mean values of degree of conversion of Luxacore Group 4, 5, 6 compared together and there is a significant difference between mean values of degree of conversion of Clearfil Photocore groups and Luxacore groups compared together. There is a significant association between microleakage and groups 1, 2 and 3, and also with groups 4, 5 and 6. Conclusion: Degree of conversion of Clearfil Photocore (light cure) was significantly higher than Luxacore (dual cure) at all cavity depths. Microleakage was significantly higher in Luxacore than in Clearfil Photocore.