In this report we propose a methodology for cost estimation for ontologies and analyze cost factors implied in the engineering process. We examine the appropriateness of a COCOMO-like parametric approach to ontology cost estimation and propose a non-calibrated ontology cost model, which is to be continuously refined along with the collection of empiric data on person month efforts invested in developing ontologies in real-world projects. We further describe the human-driven evaluation of the cost drivers described in the parametric model on the basis of the cost models’ quality framework by Boehm[5]