Heat oven to 250 degrees. Combine cereal and pecans in 13" x 9" pan. Set aside.
Combine corn syrup, brown, sugar, and butter in sauce pan. Cooke over medium to medium high heat until boiling. Remove from heat adn stir in vanilla and baking soda. Stir. Pour over cereal and stir to coat evenly.
Bake 1 hour, stirring every 20 minutes. Spread onto wax paper until cooled. Then break up larger pieces and store in air tight container.