Yes , in India you can legally adopt a child if you are a single male or female. The adoption laws are basically governed by three legistations;
1-Hindu Adoption and Maintenance Act, 1956
2-Guardians and Wards Act, 1890 (the act only confers the status of a gaurdian and ward and not child and parent)
3-Juvenile Justice Act of 2000 (the act allows both Hindus and Non-Hindus to adopt and confers the status of parent and child)