While there has been a rich body of literature on knowledge management, little research has been reported that defines the dimensions and operationalization of the complexity of knowledge management tasks. Based on literature reviews and field study observations, we conceptualize knowledge management task complexity as consisting of six dimensions: component complexity, interactive complexity, task novelty, task non-routineness, task difficulty, and lack of task information. Using a systematic instrument development process with interviews, observations and survey data obtained at Miami-Dade County Emergency Operations Center (MD-EOC) in Florida, we developed measures of the six dimensions for knowledge management tasks in the context of emergency management. The final instrument demonstrated sufficient reliability and construct validity. Implications of our conceptualization and measures of knowledge management tasks to research and practice as well as directions for future research are discussed.