This study sought to establish the effect of performance management systems on employee productivity at KEFRI. Specific objectives were to: establish the effect of performance appraisal on employee productivity; establish the effect of performance monitoring on employee productivity; find out how communication and feedback affect employee productivity and to establish how performance contracting affect employee productivity in KEFRI. The study was conducted through correlational research design. Target population consisted of vaious employees, being HR managers, research and development officers, administration and finance staff, enterprise staffs, and supply chain officers. Yamane's formula was used to obtain a sample size. Stratified random sampling was used to select study respondents. Questionnaire was used for data collection. Validity of instrument was realised through incorporation of opinions of the supervisors. Reliability was attained through test-retest during a pilot study involving randomly selected employees from the organization. Multiple regressions was used to compare the relationship between coefficients of performance management practices and employee productivity. Findings revealed that there was a moderate level of employee productivity, while performance monitoring and performance contracting both have had moderate effects on employee productivity. However, performance appraisal and communication/feedback had high effects on employee productivity. All the variables had significant effect on employee productivity hence the hypotheses that performance appraisal, performance monitoring, communication/feedback, and performance contracting have no significant effect on employee productivity were rejected. The study concluded that performance management system is a significant predictor of employee productivity. It was recommended that employees be involved in designing both performance monitoring and contracting practices to align them with their own capabilities. Further research need to be done on the effects of employee involvement in designing performance monitoring and performance contracting practices on employee productivity.