This manuscript by Hoshyaripour et al., entitled ‘The Atmospheric Composition Component of the ICON modeling framework….’, provides a comprehensive and updated overview of the ICON-ART model version 25.04, with a particular focus on recent developments in key components such as emissions, chemical mechanisms, and aerosol processes. It further details the coupling of these components with the physical core of the model, aimed at enhancing the representation of aerosol–radiation and aerosol–cloud interactions. Additionally, the paper outlines the structural organization of the model code and evaluates its computational feasibility.

This work is thus essential for gaining an in-depth understanding of the ICON-ART model architecture and serves as a valuable reference for users seeking to become familiar with its structural and coding framework. A concise review of the relevant literature related to the individual components of ICON-ART is also provided. The manuscript effectively demonstrates the model’s capability in simulating aerosol interactions with both radiation and clouds, and discusses the mechanisms through which such interactions are implemented across different model components. Overall, the manuscript is well written, and the mathematical formulations are presented in a clear and concise manner. Upon addressing the issues and suggestions outlined below, this manuscript may be considered suitable for publication.

The large number of the acronyms has been used in the whole manuscript and it is suggested to add a separate Appendix describing this manuscript. The caption of the Table and Figure could be modified to be self-explanatory. e.g., Table 1-2 give the brief overview of the Basis v Implementation. It can re-written what basis is about etc.

As noted in lines 43–45, previous work with ICON-ART has been acknowledged, while this manuscript aims to present an updated overview. However, it would be helpful to clarify which components are entirely new in the version 25.04 and which represent updates to existing implementations. For instance, while the Online Emission Model (OEM) is mentioned as part of version 25.04, the manuscript does not clearly indicate how this anthropogenic emission component was handled in earlier versions. In contrast, Section 2.3, which covers volcanic eruptions, provides an excellent and detailed account of the updates made—offering a useful model for how other sections might be strengthened with similar clarity.

Section 5.2 provides a comprehensive description of the CCN activation and its coupling with ICON microphysics for liquid-phase clouds. While the methodological explanation is clear, given that ACI is emphasized in the abstract as a key development, this section could be further strengthened by including a brief quantitative validation or sensitivity analysis demonstrating the realized impact of ACI. The INAS-based treatment for ice-phase ACI is still under development and may be incorporated in future work. 

Emission processes such as desert dust and biogenic VOCs (e.g., VPRM, mentioned later) are not discussed in the manuscript. It is suggested to include a brief discussion at the end of these in Section 2, or alternatively, add short descriptions to Table 1 (e.g., in Basis column) to make their inclusion and treatment clearer.

Specific Comment:

Line 28-29 Page2: Repetition in the abbreviation defining, ICON, ART etc.

Line 52-53: The reference needed which describe OEM in COSMO-ART. 

Line 68: Hermes or HERMES (High-Elective Resolution Modelling Emission System)? 

Line 67 Is there anything missing in the line ‘[e.g.,][]’ ?

Line 175-180: The new Grythe et al. (2014) sea‐salt emission parametrization is introduced in Section 2.4. A brief quantitative or visual comparison with the Monahan scheme could further illustrate the improvement in sea‐salt emission estimates.

Line 211: Meccatracer?

Line 424-426: The sedimentation terms in Equations (12)–(13) use inconsistent symbols (Φ → Ψ). Please ensure consistent notation for the prognostic variable, either using the hat over Ψ throughout or omitting it consistently.

Line 515: ARI is already defined earlier in text.

The sub‐labels in Figure 9 are difficult to read due to the white font color. Consider enclosing the letters in a contrasting box or background to improve visibility.

Line 697: Online Emission Module→ OEM

Line 712-713: vegetation photosynthesis and respiration model (VPRM)?

Appendix D and E do not seem cited or discussed in the text.