Step 1: About the interim government.
The interim government of India was formed in September 1946 under the leadership of Jawaharlal Nehru. It included members from the Indian National Congress, Muslim League, and other communities.
Step 2: Finance portfolio.
Liaquat Ali Khan, a prominent leader of the Muslim League, was given the crucial portfolio of Finance in this interim cabinet. This allocation was a matter of political significance at that time.
Step 3: Conclusion.
Hence, the Finance Minister in the interim government was Liaquat Ali Khan.
\[
\boxed{\text{Liaquat Ali Khan}}
\]