With the high demands on research ou tputs, academicians are under pressure to cope with their teaching responsibilities as well as other managerial and administrative responsibilities that may affect their in role and extra role performance. Four hundred and thirty one (431) academicians fr om twen ty (20) Malaysian public universities were sampled which drawn from a stratified sampling The study examined the factors affecting in role and extra role performance among academicians in Malaysian public universities. There were two (2) propose d affecting factors that being examined; namely job demands as independent factor, perceived job burnout as the mediating factor and religious perso nality as a moderating factor. The job demands, in role performance and extra role performance questi onnaire revised by Bakker (2014), while the perceived job burnout questionnaire by Demerouti (2010) and religious personality questionnaire by Krauss (2007) were adopted and adapted. The Job demands resources theory of burnout guided the study through a q uantita tive research design. Data were analysed using SPSS 23.0 and AMOS 23.0 approaches of structural equation modelling t o test the hypothesised model. The findings of this study largely supported the hypothesised relationships proposed in the theoreti cal mod el especially the mediating effect of perceived job burnout between job demands towards in role and extra role performance. The study concluded that all research objectives were successfully answered and achieved. Future studies applying the propos ed mode l are therefore recommended to be conducted at the institutions of higher learning across Malaysia in order to verify these findings.