Sayyiduna Mu'adh bin Jabal (may Allah be pleased with him) said that the Prophet (peace and blessings be upon him) said: "The blood money of a woman is half that of a man."
This has also been narrated through another route from Ubadah bin Nusayy, and there is weakness in it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الديات / 16305