Some occasions when supplications are seldom rejected.
1. When praying Tahajjud.
2. Between Adhan & Iqamah.
3. When fasting.
4. When traveling.
5. Wednesday between Dhur & Asr.
6. Friday between Asr & Maghrib.
7. In prostration.
8. Before making Tasleem.
9. During rain.
10. During battle.
Reference Al Bukhari, at-Tirmidhi 212, abu-Dawood 437, Ahmad 12174