The aim of this thesis is the conceptual design of a mobile app (CO2-app) to compare and track the CO2-equivalents of food and means of transportation. It is focused on the DACH-Region (Germany, Austria, Switzerland). For the target group, people from 15 to 39 years of age are considered since within this age group the use of mobile phones and apps is above average. Furthermore, an interest in acting in an environmentally friendly way is required. The basis of the concept is the analysis of the target group. To identify the needs of the target group in terms of a CO2-app, an online survey was developed. As part of the market analysis, it is discussed which apps with similar contents as the CO2-app are present. Some of these apps, as well as selected mobile tracking apps, are analysed for their strengths and weaknesses to identify strategies for the CO2-app. Research was conducted to define the data available for the Life Cycle Inventory (LCI) and the Carbon Footprint Equivalents (CFPe) of food and means of transportations and how well they can be combined. Processed foods have been excluded from the study due to their high complexity. Additionally, it is checked whether it is possible to provide the content wanted according to the survey with the data available. Finally, an example of the main features and contents of the app are presented, including a sitemap and wireframes. Throughout the survey a total of 297 useable answers were received, of which 49 % were identified as reflecting the target group. Also, 72 % of the respondents are interested in a CO2-app, however, it should be considered that the people interviewed reflect a convenience sample and the survey is not globally representative. Currently, there is no detailed CO2-calculator for food and only limited data of CFPes freely available. Looking at means of transportations, there is enough data freely available, but a mobile app for the region of interest does not exist. Another difficulty is presented by the different global warming potentials used, as well as the inconsistency concerning the part of the life cycle considered. According to the survey, the key product features and attributes are origin, seasonality, type of packaging and organic production. Using the collected data, the influence of each of these factors was estimated. It was possible to draft a concept of the CO2-app, though before an implementation, further steps have to be taken. If a consistent database is provided and some further research is conducted, the app may be developed. A consistent CFPe-basis for food has to be created and additional research to improve the data of the features and attributes of the products are necessary.