Technology readiness levels (TRLs) have received increasing recognition throughout academia, industry, and policy-making as a tool for evaluating and communicating a technology's maturity. Conventional scales are unspecific to technologies as they aim at evaluating and comparing technologies combining different fields. Hence, they present vague descriptions which leave considerable room for interpretation and subjective choices. For the chemical industry, adaptions and specific criteria are needed for more comprehensible TRL ratings. This paper specifies the nine conventional TRLs for the chemical industry as idea, concept, proof of concept, preliminary process development, detailed process development, pilot trials, demonstration and full-scale engineering, commissioning, and production. Adjusted descriptions and additional criteria with detailed indicators are presented, depicting the logical progression of a typical chemical innovation in the phases of applied research, development, and deployment. The specified TRLs facilitate evaluation and communication of a technology's maturity and substantially improve the basis for data availability-based assessment.