Is us dollar valid in Peru?

Yes, the US Dollar is accepted and used in Peru, alongside the Peruvian Sol. Both currencies are widely accepted for payments, and you can exchange your US Dollars at banks, currency exchange offices (casas de cambio), and some hotels. It's generally advisable to have some Peruvian Soles on hand for smaller purchases, local markets, and public transportation, but you won't have difficulty finding places that accept US Dollars, especially in tourist areas. When making payments in US Dollars, it's important to check the exchange rate and be aware of any additional fees or commissions charged.