EmotionSense collects information about where users are, how noisy the environment is and whom they are communicating with. It then combines this data with the user's own report about mood, reports the BBC.
The app is part of a project to see how mobile phones can be used to improve health and well-being.
Mood-tracking apps already exist but the team from the Cambridge Computer Laboratory think this is the first time that user-input data and phone information sources have been combined.
Dr Jason Rentfrow, a senior lecturer in the department of psychology at Cambridge University said the aim here is to use a more flexible approach, to collect data that shows how moods vary between people.
When the app is opened for the first time, a sensor that tells the researchers what time of day it is is unlocked. The app spends roughly a week collecting data from this sensor and testing it against the user's emotional state. At the end of this, the user is asked to complete a short life satisfaction survey, which unlocks a new sensor, after about eight weeks.
Lead researcher Dr Neal Lathia said the app has been designed as "a journey of discovery" for the user to give them a step-by-step guide to what might be influencing their mood swings.
The system that allows users to input their own data about how they are feeling has been designed by psychologists.
The app is expected to be used by doctors as a therapeutic tool as well as by individuals to work out the times that they are most stressed, for example.
Initially the app will be available only for Android phones but the team is working on a version for other smartphones.